View Full Version : TAMD40 tempearature question

07-19-2009, 04:18 PM
"For the last 4 months I have been running a 26ft charter boat (scuba) with TAMD40A. Engine has thru-hull exhaust, and raw water pickup from the grate in the hull. Run great with no smoke, fresh oil and filters. With Morten's advice i was able to get the correct prop for it (16x15) and have been very busy lately, with more and more passengers. I have noticed lately that when I fully load up the boat (with about 2000 lbs of people/tanks/gear), i lose some top speed (as expected) and i also run approx 25F hotter (expected as well??).

Empty boat (just me and full tank) 175F @ cruise RPM
Full boat (me, full tank, + 2000lbs) 205F @ cruise RPM

I run continuously @ cruise for approx 45min to an hour to my furthest dive spot. Temperature reading is always solid and steady, and gauge doesnt fluctuate. It never got above 205F (~95C).

Is this normal for the boat to run approx 25F/30F hotter when loaded down?


07-19-2009, 10:46 PM
"If temp is stable and does not continue to climb I would not worry.
If Your cruising RPM is the same with boat empty or loaded, the engine will run with a higher throttle (fuel delivery) setting when boat is loaded."

07-20-2009, 07:53 AM
"Thanks Morten. Yes temperature is very stable and does not climb past 205F no matter how long I run it loaded.

I was thinking about using some additive in the coolant (like Reline WaterWetter) to help lower temperature some? I have cleaned the raw water intake grate, and will keep an eye on coolant too, going to flush it with new fluid in about 30 hours @ next oil change."

07-20-2009, 08:04 AM
"Two things are important and often left a bit behind.
Oil takes about 30% of the total cooling, so keep oil-cooler clean and use a high grade oil. Next is air, both temp and 'volume'. Be sure the engine gets plenty of air, and if possible not from transom mount intake as that will even include quite some water mist that clogs up the air filter."

08-01-2009, 01:51 PM
"I switched back to the OEM Volvo 16x15 prop (was fouled up, and went to the shop for reconditioning), and now temp is 195F @ cruise when loaded.

I am at about 90 hours of run time, so oil change is coming up in few hours. I found a small leak under the turbo compressor plastic intake pipe (looks like oil return line gasket or something?), and another small leak at the raw water pump (and I put a brand new seal in there??), gotta fix those.

As for the air supply, my engine doesnt really have any direct air ducts bringing fresh air to the intake filter. I am debating cutting a hole in the engine cover in the intake corner and installing a stainless vent, to allow as-fresh-as-posslible-air to the motor.

Have another question. My ocean access is thru Boynton Inlet (please watch the video: http://www.youtube.com/watch?v=XUOsgXg7Gwg ("")). Its like whitewater rapids in there during incoming/outgoing tides....18ft fixed bridge, and some 130ft wide...tight fit. Sometimes when making a sharp turn (when entering inlet, and while in the inlet's turbulent water), or when in quartering following seas, or when crossing another boats wake (while both boats are going in the same direction), I feel the prop spin more freely and bump up revs approx 100-300rpm. Kind of like catching some propwash aerated water. Makes the boat dig in back, and throws me off the plane. I dont remember the boat doing that before, so I was kinda concerned that it might have something to do with the outdrive (280SP).

Thanks in advance as always."

08-01-2009, 07:48 PM
"That temp goes down at less engine load is normal. Having had a peak at the video, I understand that your prop may do a spin out from time to time. You may probably have to cup it to reduce that effect."

08-02-2009, 09:49 PM
"Today 3 passengers temp 180F
Yesterday 5 passengers temp 195F

Temp stayed steady. I am dumb for leaving that generic spare prop on there for so long....now i finally realize how crucial is the OEM oversize blade design.

I am getting prop spin out sometimes when just driving up the calm intracoastal, with no boat traffic around. Very weird, I do not remember ever getting it before unless it was in turbulent water or i drop back from a wave and choke out the prop.

This happened with two separate propellers, which makes me think its not the prop hub that is spun. There is no rule to it, it powers nice and strong thru the inlet, and then spins out when cruising up the intracoastal. Any idea what might be causing it? It almost never happens below 3000rpm, and is happened handful of times for no apparent reason @ 3200pm or so.

Outdrive fully serviced 100 hours ago, with new fluid, all correct washers and specs, and pressure tested.

Thanks in advance!"

08-02-2009, 10:49 PM
"As for the prop 'spin out'.
What is happening, is most likely that the prop is beginning to loose its blade profile. Almost normal for alu-props of that dia on a diesel with that torque. The blades simply 'bends' and looses shape over time. When you get your Volvo 'Mikey Mouse' prop back, send the spare to the shop and have it checked out. At the same time ask them to make a 'soft' cup.
As for the temp, it seems to be under control. As a double security and check, you may install another temp instrument with the sensor at the raw water output from heat exchanger. If that starts peaking up, you know you are heading into a raw water problem. You may just use a contact sensor as used on outboard on the water tube."

10-02-2009, 05:00 PM

Do you have any 40b parts? I am looking to cxhange out tmd40b to a tamd40b. I need the oil cooler and the piping. I can give you the part numbers if you need them"

10-02-2009, 09:58 PM
I would have been looking for a complete 41 instead.

10-03-2009, 10:53 PM
"I actually just found complete running TAMD41P-A at a great price, and am preparing the boat for the swap http://www.marineengine.com/discus/clipart/sun.gif"

10-03-2009, 11:09 PM
"Keep us updated, and fasten your seat belt!

10-05-2009, 10:59 PM
"Can't wait!!!

Currently I have 280 SP drive. Electro/mechanic tilt. 41P-A has the aftercooler pipe in the same location it seems...what are my options (what needs modified) to install 41P-A and keep the 280 drive with the tilt?? I also have 290 DP-S drive but need to get boat back in the water quickly (for work) and would rather keep it simple and use 280 SP drive thats already on the boat....280SP shaft is big and sturdy, what I need for commercial use.

Thanks for your advice! http://www.marineengine.com/discus/clipart/thumbs_up.gif"

10-05-2009, 11:23 PM
"Should be a rather straight 'bolt-on' conversion.
Personally I prefer to remove the drive and lift out engine with bell housing, to avoid bending shafts.
One 'problem' that might arise is cooling as You will be on the limit if using drive for supply.
Might thing of a 'big' through hull pick up.
The 41 'eats' airfilters, I used to throw them away and use a 'mosquito' net instead."

10-06-2009, 12:09 AM
"I have to remove the drive to replace the bellows (have some water intrusion, and starter is getting water sprayed onto its shaft inside bellhousing), so engine will be lifted with the drive off. Boat is already setup for thru-hull pickup for water, and transom exhaust (nothing goes through the drive).

The aftercooler pipe that connects it to compressor turbo side seems to sit exactly in the same position as where my current tilt microswitch box is situated....hopefully it clears so I can keep the current outdrive

I saw how small the filter is....going to replace it with mosquito net as well"

10-06-2009, 04:19 AM
"If the 'black box' for the tilt makes a problem, I have in some occasions 'moved' the content to a bracket on the transom to make better space.
Don't let minor problems spoil your day!"

10-06-2009, 06:45 PM
I have a mercruser 190. Would like to know how to winterrize

10-10-2009, 11:16 AM
"Since 41P is not ready for installation yet, i removed the TAMD40A out of the boat, serviced the drive and replaced the bellows (torn), and all the bearings/seals, including the rear main seal. I also cleaned the bronze intake grate (thru hull) for raw water, it was partially plugged up with coral growth. I was very excited and expected the motor to run MUCH cooler than before. Put everything back together, and went for a test run. Started it, noticed that raw water impeller housing cover was warmer than normal, shut it off and replaced the impeller (one blade was broken, and I removed old impeller and also found and removed broken blade). Now cover is cool to the touch. During the run, it was just me on the boat, and temp climbed to 200F in under 2 minutes of cruising at 3000rpm! http://www.marineengine.com/discus/clipart/uhoh.gif
It used to take 20-30min of cruising for temp to slowly climb towards 200F. Temperature was also VERY slow to go back down, where it normally used to fall back to 150F as soon as I would come down to idle speed. Right now even at idle temp stays in 170-180F range.
Radiator cap had alot of pressure under it, and it coughed up some coolant when I carefully opened it. I also have a wooden wedge behind the end cap on the HE.

I dont have the IR heat gun to check temps in various places on the motor, can anyone suggest where to start looking? Thanks in advance!!!http://www.marineengine.com/discus/clipart/rain.gif"

10-10-2009, 06:00 PM
My guess is air lock... try to purge system of air and refill and try again with another run.

10-10-2009, 07:51 PM
"200F (93C) OK, 210 a bit too high at full load.
175F (80C) at idle perfect as well!!
Note that this engine has 2 thermostats with DIFFERENT opening temps. One to control at idle, the other for high speed. They work in parallel however in the same system. Running in extreme hot water, you may change both to the lower type, but it might increase smoke.
How was performance?"

10-10-2009, 08:34 PM
"Morten, there was no performance, it would overheat in 2 minutes and I was unable to run the boat further than that. I could literally watch the temp gauge move up quickly to over 200f and throw temp alarm. Coolant was boiling. I think its either air lock or major blockage in raw water system....I will try to test and eliminate possible causes one by one starting with intake graten to the exhaust elbow. It was running warm beforte but nothing rediculously hot like this.

Thanks for suggestions. Is port or starboard thermostat the one with higher temp opening? Would removing thermostat or both help any?"

10-10-2009, 08:59 PM
"Firstly an IR gun is close to a must in this case, as it gives you the possibility to monitor the raw water temp out of the exchanger. If that keeps climbing, you have a raw water problem.
It does not matter if it is stb or port thermostat which is the lower/higher one as they are in parallel. You have to remove and read the specs on them. They are probably stamped in C degrees, but do not remove them.
Double check the venting line from turbo to tank. The banjo bolts have a tendency of clogging up in the small holes and not vent out properly.
Do you still have the exhaust brake/solenoid with the flapper in the exhaust outlet?"

10-10-2009, 09:32 PM
"I don't think I have exhaust brake flap, its just the elbow after the turbo and then some simple piping to the transom rubber flap. I will buy ir gun asap. Will not remove thermostats. Has to be air lock or something clogged bad....maybe exhaust elbow? I will vent at turbo coolant banjo first see what that does....tnx"

10-10-2009, 09:39 PM
"Went in and double checked the 41P cooling.
It seems they have changed the thermostats to 2 equal, 81C which gives about 178F. At least your idle temp is perfect.

10-10-2009, 09:41 PM
"The turbo ventilation hose I talked about earlier is the #20/21. It might be some different versions out.

10-10-2009, 09:50 PM
"Not sure how engine removal could create air lock in coolant side, that system remained closed....is there air lock possibility in raw water and how do I vent that?"

10-10-2009, 10:03 PM
The whole cooling 'problem' both on this engine and the previous one might be related to your through hull water intake.
Where is it located?
Do you have a pick?
If possible run a clear plastic hose between intake and filter/pump and see if any air bubbles appears.

10-10-2009, 10:03 PM
"Morten these problems are on my old tamd40a not on 41p. 41 is not ready for swap yet, gotta service the 290dp first.
My idle temp used to be 150f"

10-10-2009, 10:51 PM
"The 40A had the different thermostats, 70C and 76C.
My guess is that one of the thermostats are hanging, not opening.
Is below pick relevant?

10-10-2009, 11:56 PM
"Yes, that looks exactly as my system on 40A.

Thru-hull pickup is 3" x 8" brass grate, i cleaned it really nice. New impeller. No leaks of coolant or raw water.

I will start checking things out in the morning, and will report back. Thanks for your help and ideas"

10-11-2009, 11:09 AM
"Cleaned heat exchanger with long wire, about 20 percent of tubes were clogged. Removed one thermostat temporarily. Ran motor at idle with HE front cover off, and there was good water flow...this tells me oil cooler and HE are relatively clean and are flowing raw water. With HE front cover off I pulled hose on exit side of exhaust elbow, and did not see water coming out of there...and when I put HE back together it still didn't seem like exhaust elbow was flowing...and it kinda makes sense, it seems like my raw water is stuck in the motor. Should I try to clear/clean the exhaust elbow? Just run wire thru stainless sleeve and clear blockage, or just buy new and replace? I hope I am narrowing this down....ran boat today and its 175f at anything below 2000rpm....over that it shoots to 210-220f and is very very slow to cool off once I get back down to idle."

10-11-2009, 08:11 PM
"If water is flowing OUT of heat exchanger and INTO elbow but nothing in exhaust, pull the elbow.
Clean if possible, but most likely time for replacement."

10-12-2009, 01:34 PM
"Checked exhaust elbow, half of the stainless screen openings were rusted shut. Put garden hose to it and it was still flowing ok, but will need replaced. Next I ran engine with the hose that enters elbow rerouted into a bucket....there was flow, but not nearly what I expected to see. Then I pulled the end cap from the HE, cap looked fine, but as soon as I removed the cap coolant slowly drained through HE rear opening....I checked the overflow and it was empty (was full before end cap came off). HE is shot, right?"

10-12-2009, 08:11 PM
"This is the exhaust elbow, 40% rusted shut....
http://i37.tinypic.com/2ptsapt.jpg" ("]http://i36.tinypic.com/2qdwlew.jpg"[/url]

This is the HE end cap....
http://i37.tinypic.com/30mv9s0.jpg" ("")

HE is clean, all passages are good. Tomorrow I will remove oil cooler and clean it. Raw water pump works good and pumps alot of water even at idle, hose from RWP to oil cooler is clean with no blockage.

I was thinking of temprarily using the 41P exhaust elbow for test purposes (block off extra pipe with rubber cap). Would that work? Is the turbo outlet size the same at 40A? Tnx"

10-12-2009, 08:24 PM
"I doubt the cooler is 'shot' you would have lost all water when running.
Only way to test is to block outlet and pressure at inlet, or put end cap back, remove hose, attach a radiator pressure tester on expansion tank and pump pressure.
Exhaust bend looks baaaad! clean and put back.
You may shortly start engine with hoses disconnected from pump OUT, oil-cooler OUT, intercooler OUT etc, then you will see where water does not go through."

10-14-2009, 12:02 PM
"I cleaned thru-hull pickup, cleaned and inspected all pipes and hoses that pass raw water, cleaned and inspected HE, cleaned oil cooler (took apart and washed out), aftercooler has been off the motor and cleaned/resealed about 2 months ago, refilled with new coolant, checked for leaks (none). Ran today (with one thermostat still removed) and it did the same thing. As soon as I got on the plane temperature started to climb fast (up to 200F within 2 min), and when I backed it down to idle it was VERY slow to cool off. It took 10 min to get back down to 165F.

Could it be that my radiator cap is bad? One on there is about 2 months old.

Maybe there is restriction inside the metal coolant line between turbo and overflow canister?

Could the above problem(s) be causing fast heating like described?

I am running out of ideas...


10-14-2009, 04:01 PM
"Had the same problems om my two AQAD40B's. Recommend a check of the fan belt, circulation pump,raw water filter and raw water oump cam in order to exclude these causes. Good luck!"

10-14-2009, 08:27 PM
"Check raw water OUT from heat exchanger.
Run engine until 'hot', loaded.
Shift into neutral, rev to about 12 - 1500rpm.
Raw water temp should drop to close to sea temp in line with engine temp dropping.
If raw water temp drops but not engine temp, most likely an internal engine circulation problem: circulation pump!
If engine temp and raw water temp drops 'parallel', a sea water capacity problem. Check flows as described earlier.
I take it that you have checked for exhaust gases in the internal cooling system to eliminate a blown head gasket etc.
IR gun????"

10-14-2009, 10:43 PM
"I am buying the IR gun tomorrow. I will check as advised, and report back with readings. How do I check for exhaust gasses in coolant??

Today I cracked the turbo banjo to vent coolant when engine started to run hot, it sprayed some coolant and vented some air....then I cracked the radiator cap and it also vented some pressure from there....the line might be blocked I think.

I also pulled the plug from the bottom of the AC, and there was excellent flow of raw water shooting out....I then pulled lower hose on HE end cap, and flow didnt seem that impressive....wonder if that has to do with opening diameter (AC hole is approx 1/2 the size)...."

10-14-2009, 11:40 PM
The coolant will normally smell of exhaust and be mixed with oily sludge if a blown head gasket.
Have you ever removed the front cap on the heat exchanger?

10-15-2009, 08:09 PM
"Here is the report.

Coolant is green, and has no traces of oil (no oil sheen on the surface).

I forgot to mention that when I installed the motor back after bellows replacement and service, I tightened the belts via alternator, engine was making these pinging metallic noises from the front of the motor (not harmonic, totally random and usually at low revs, went away at higher revs). Noise stopped when I loosened the belts some. Can it be possible that the metallic noises were from circulation pump bearings going bad?

As for the temp, I have made sure tube from turbo exhaust housing to overflow tank is clear of any obstructions, and that radiator cap is good.

As soon as I would get on the plane, in 2-3 minutes @ ~3000rpm , engine would get to 195F+. I used IR gun to check the temp along the raw water route:

Raw water (sea temp) 88F
Raw water before RWP 95F
Raw water after pump 93F
Raw water after OC 110F
(Oil Cooler body 184F)
Raw water AC top hose 116F
Raw water HE out pipe 155F
Raw water Ex elbow 147F
Overflow tank temp 198F

When I would keep it at ~1400rpm, with gun pointed at HE out pipe, temp would sit ~ 150-155F. Metal overflow canister temp would also sit ~190-192F. When I let it go back to idle, VERY SLOWLY it would come back down to ~165F.

Thanks for any suggestions"

10-15-2009, 08:13 PM
"I have removed HE front cover before, it is clean, and every tube is clean (rodded 20% of clogged ones out with coat hanger). Now its clean

Above test report was done with AFT thermostat removed."

10-15-2009, 09:39 PM
Pull the circulation pump.

10-16-2009, 08:25 PM
"Pulled the circ pump, it checked out fine (no leaks, no play in the bearings, spins freely).

Tested and reinstalled both thermostats (70C FWD, 76C AFT).

I am using newish 16 LB radiator cap.

Tested the boat afterwards, same temperature and behavior like in the previous report.

Next I have to test the RW pump, how can I know its u pumping enough volume? What to look for internally?"

10-16-2009, 10:10 PM
Did you check that the impeller on the circulation pump had the correct clearance to the housing (no cavitation marks) and impeller had not spun or slipped at the shaft?

10-20-2009, 04:06 PM
"Removed and checked RWP, cam is good, impeller is good, no water/oil/air leaks, pumps alot of water. Reinstalled.

Checked impeller on circ pump, looks good, its pressed on properly (not spun or broken), no unusual marks on the housing, clearance is tight, bearings are good. I can see the coolant under the radiator cap circulating when engine is running. I also get spray out of turbo exhaust housing banjo when running, stops as soon as I shut down the motor. This tells me circ pump is working.

Today I ran Cascade dish powder thru coolant system, twice (about 1 cup each time) for an hour, mixed with 100% fresh water, up to 200F. Drained after each run (drain plug under HE), and first flush was brownish, second flush was orange-ish, and last flush with fresh water hose was clear water. Refilled with 60/40 coolant.

Replaced my 16 LB radiator cap with known good 14 LB cap.

Boat still heats up from 150F to 200F in under 2 minutes @ 3000rpm.

I am running out of ideas.

41P is going to be ready for installation by the weekend....but it worries me that 40A is running like this, I dont want to just pull it and have it sit in the garage, on the bench its going to be much harder to diagnose (unable to put load on the motor)....and 40A has to go into the donor boat where 41P came from....

I am running out of ideas...."

10-20-2009, 04:53 PM

I'm no expert, but it sounds like you have good water/coolant flow, but keep in mind, your oil flow is just as important for cooling the engine. I'm not sure, but fuel return might also be an important coolant. Just a thought, I've been following your trouble-shooting with interest. Hope you solve it soon.

10-20-2009, 04:57 PM
"Check that the raw water hose between raw water pump and water inntake not get sucked flat because of lost strength. Do also scheck front end of oil cooler for zink anode remainings, and finally check cam in raw water pump for excessive wear that reduces pump effect. Wishing you every luck!"

10-20-2009, 05:59 PM
"Thank you guys for suggestions.

My hoses are ones with wire in them (hard marine exhaust type), so there is no deformation or collapsing under pressure or under suction.

Oil cooler had few barnacles and few small impeller pieces, but i flushed that all out. I even pressed out the element and cleaned it with parts cleaner solution (it looked new) inside out. New o-rings and it went back together...its clean as a whistle.

Cam in RWP is nice and thick, it bends the blades nicely and sucks/pumps water hard.

Engine runs fine, but I am also starting to think it might be fuel/timing related...how can I check fuel return?

My racor is brand new 2 micron. Tank is half full. Oil is 70 hours old, correct level."

10-20-2009, 09:38 PM
"Your testing seems a bit unorganized, sorry to say.
Read my previous post.
'We' need to establish if you have a raw water problem or a internal circulation/capacity problem.
With the IR gun at hand, and perhaps an assistant do the following exactly to the point.
You need to be precise and systematic in the testing to sort this out properly.
Start the engine, shift in gear and run. Monitor the raw water temp OUT of heat exchanger AND engine temp.
Both temps should climb almost linear. If engine temps keeps climbing, and raw water temp stops climbing, you have an internal circulation problem!
If/when engine overheats, immediately shift into neutral, rev to about 1500rpm, keep monitoring engine temp and raw water temp. Both engine temp and raw water temp should drop next to parallel.
If raw water temp drops drastic and engine temp drop lags severe behind, you have an internal problem. If they both drop parallel, you have a raw water capacity problem."

10-21-2009, 01:28 PM
"Sorry abt that, I was all over the place trying to sort this out.

Before the test I installed brand new Volvo impeller, and made sure blades are oriented to turn clockwise.

Here are the temperatures taken every ~20sec (the time it takes to aim IR gun, hold 5sec to get good reading on EX OUT pipe, then 5sec on HE overflow canister base, and write down results). Hopefully this chart formats out so it's readable:


Engine temp - Raw Water HE OUT temp
---107-------- ---84----
---119-------- ---87----
---131-------- ---87----
---157-------- ---87----
---167-------- ---100---
---175-------- ---125---
---183-------- ---130---
---195-------- ---140---
---200-------- ---145---

1500rpm @ neutral

Engine temp - Raw Water HE OUT temp
---200---- ---145----
---200---- ---143----
---197---- ---142----
---193---- ---140----
---190---- ---137---
---188---- ---140---
---187---- ---140---
---185---- ---139---
---181---- ---137---
---180---- ---138---
---179---- ---137---
---176---- ---137---
---177---- ---139---
---176---- ---133---
---173---- ---130---"

10-21-2009, 09:04 PM
"As I read this, you have a raw water capacity problem.
On the 'in gear/loaded' it seems to be a spiking in the raw water out temp around engine temp 160.
The 'unloaded/neutral' temp diagram unfortunately stops before the critical 160 temp, but on the other hand it drops rater parallel to the engine temp. the raw water temp should have dropped in a much steeper curve relative to engine temp.
Going back and looking at the end-cap pic:
Does it seal properly towards the heat-exchanger?
Note that water flows 'forward' in one half of the exchanger and then back in the other half. If the two halves of the exchanger is not properly sealed off by the center seal in the end-cap, this might create a problem."

10-21-2009, 09:23 PM
"Thanks Morten.

I understand how raw water flows, the cap looked like this when I removed it http://www.marineengine.com/discus/messages/12494/295443.jpg, I then sandblasted the inside of it and removed all the gunk, it came out pretty clean. Flap was not deformed, and it "fell" into place easily when I put it back on the HE. I drew a marker line on the outside of the cap so I know where the flap sits, so it would not bend or miss the divider. Here is how HE core and divider plate looked http://www.marineengine.com/discus/messages/12494/295444.jpg

I can try adding brass sheet folded over to make a tighter seal?"

10-21-2009, 09:51 PM
"It is a bit difficult to judge all possibilities just from the pics, even if they are good.
Might it be a possibility that it leaks by on the sides?
The cap is quite some years and might have gone 'hard' and malformed.
On the other hand you have earlier mentioned that the flow OUT seems to be less than the flow IN?"

10-29-2009, 03:41 PM
"I made a pressure gauge, and checked pressure along the raw water system.

Pressure @ idle:

front of Oil Cooler
24-26 PSI

front of Heat Exchanger
-8 PSI (????)

bottom of Aftercooler
21-24 PSI

I now know raw water pressure is entirely too high. I could not get pressure reading from the front of the HE, tried 4 times to get readings on all 3 locations, using the same gauge that measured 4 times correctly on OC and AC - but would not read anything on HE front cover. I was using the zinc hole to attach gauge and measure.

As I would raise RPM, both OC and AC readings would jump over 30 PSI, and HE reading would stay -8 PSI (vacuum?). How is this possible? When I remove the gauge/zinc entirely, there is some water coming out of the HE front cover, but doesnt seem like much.

I have also tested the HE end cap, and even at 3000rpm its not flexing at all towards the AC.

PS I am still waiting on new exhaust elbow to show up in the mail, so test was done with old exhaust elbow.

Any ideas? Thank you in advance"

10-29-2009, 08:49 PM
"Your readings partly confirms my theory.
The zink is going into the the front end heat-exchanger if not mistaken.
If a leak between the chambers (rubber end cap) it may indicate that most of the water is entering the lower part, then leaks between and goes out without passing through the exchanger."

10-29-2009, 10:30 PM
"Thanks Morten, I will try to reinforce the end cap like shown in the photo, but with brass plates....to force the water across.


Do you have any ideas why pressure is so high in the rest of the system? What might be causing it?"

10-29-2009, 10:44 PM
"Sure you do not have a major 'blocking' in the pipe going to the exchanger from aftercooler?
As for the end cap, I do not quite remember the number of clamps holding it. However I would have tried putting a clamp that keeps the end-cap sealed properly to the protruding part of the exchanger element as well, to eliminate flow-by on the sides. I do not think the center divider is where the biggest problem is."

10-29-2009, 11:15 PM
"I will remove AC again and check internals and all pipes. End cap has two clamps, larger outer (FWD) one seals raw water, smaller inner (AFT) one seals coolant away from raw water. Thanks for suggestions"

11-06-2009, 10:48 AM
"A/C raw water passages were completely clogged with barnacles:

http://i34.tinypic.com/zwn91v.jpg" ("")

After trip to muriatic acid tank, AC is back together and boat is running cooler than ever now!


11-06-2009, 07:19 PM
Good to hear 'we' finally found it!
Happy boating.