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TAMD40 tempearature question

"Cleaned heat exchanger with l

"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."
 
"If water is flowing OUT of he

"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."
 
"Checked exhaust elbow, half o

"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?"
 
"This is the exhaust elbow, 40

"This is the exhaust elbow, 40% rusted shut....
http://i36.tinypic.com/2qdwlew.jpg"

This is the HE end cap....
http://i37.tinypic.com/2ptsapt.jpg"
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"
 
"I doubt the cooler is 'sh

"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."
 
"I cleaned thru-hull pickup, c

"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...

Thanks"
 
"Had the same problems om my t

"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!"
 
"Check raw water OUT from heat

"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????"
 
"I am buying the IR gun tomorr

"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)...."
 
The coolant will normally smel

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?
 
"Here is the report.

Coolan

"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"
 
"I have removed HE front cover

"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."
 
"Pulled the circ pump, it chec

"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?"
 
Did you check that the impelle

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?
 
"Removed and checked RWP, cam

"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...."
 
"Stringer,

I'm no exper

"Stringer,

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.
Bob"
 
"Check that the raw water hose

"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!"
 
"Thank you guys for suggestion

"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."
 
"Your testing seems a bit unor

"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."
 
"Sorry abt that, I was all ove

"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:

RUN
_______

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---"
 
"As I read this, you have a ra

"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."
 
"Thanks Morten.

I understa

"Thanks Morten.

I understand how raw water flows, the cap looked like this when I removed it
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
295444.jpg


I can try adding brass sheet folded over to make a tighter seal?"
 
"It is a bit difficult to judg

"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?"
 
"I made a pressure gauge, and

"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"
 
"Your readings partly confirms

"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."
 
"Thanks Morten, I will try to

"Thanks Morten, I will try to reinforce the end cap like shown in the photo, but with brass plates....to force the water across.

295901.jpg


Do you have any ideas why pressure is so high in the rest of the system? What might be causing it?"
 
"Sure you do not have a major

"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."
 
"I will remove AC again and ch

"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"
 
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