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Fill Recommendations for Sendure Heat Exchanger

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mike33egg

Member
I have been having sporadic heat issues with my 318's of late, and decided I needed a bit more information. This is my first fresh water cooled set of engines. I'm trying to understand how FULL to fill the Sendure heat exchangers on both engines. Are they supposed to be filled to the neck under the pressure cap ?

Neither exchanger was full to that point, and it occurred to me that I might have air in the system if not. It appears that the level in the vertical tank is actually below the top hose connection on the heat exchanger.

Also too, is there an actual procedure to bleed the system while refilling it ?

Thanks in advance

Mike
 
Mike, minus expansion, yes..... they do need to be completely purged of air, and filled to the top!
However, do your H/E's (heat exchangers) have a coolant recovery system?

When the engine heats up, the coolant expands. Without a recovery system (of which requires a special pressure cap) the H/E will often puke the expanded coolant out.
If no recovery system, the H/E will appear to become low on coolant........ and it will be low!
If no recovery system....., you may want to add them.... and I doubt you'll have this issue any longer!
( They must be placed at an elevation close to the H/E coolant level to perform best, IMO! )

Also, if it's been a while since these H/E's were cleaned, rust scale debris build up in the bottom of the E/G (ethylene glycol) side of the tube bundle can and will cause the engine to run warmer than need be..... thus more expansion of the coolant!
Unfortunately, this side of the tube bundle is inaccessible to the average Joe!

You can, however, remove the H/E and do a cleaning of sorts by adding a flushing chemical, and by shaking the crap out of them!
Do this several times!
Then catch what you dump from it each time, and examine it.
That will be your "tell tale" sign!
Then neutralize the chemical....... re-install...... fill with fresh E/G coolant!
It may require a cycle or two to purge the air..... just as with a car/truck!


BTW, the sea water side on most of these H/E's IS accessible and can be "rodded" out!
When contaminated with marine growth/debris....., this too can cause one to not remove enough heat from the E/G coolant!
.
 
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Rick, this H/E does have a coolant recovery tank, although where located, there's a kink in the hose from the cap to the tank. I'll be relocating it. The fluid level seemed low to me, which as I stated previously, was actually below the top hose connection, which to me indicates a possible source of air into the system.

This episode began while I was using my infrared heat gun to observe temperatures on the running engine. All seemed fine until I began to compare temps from one log to the other. One was at 157 degrees, the other was 100 degrees more !! I dumped additional antifreeze into the tank, but still didn't fill it to the rim under the cap, ran the engine again, same results.

Decided that maybe I had a blocked log. Disassembled the end cap from the front of the log, removed the riser and down angle parts and found the log completely clear, no rust scale, clogs, debris, nothing. The riser was dirty with scale and rust, and the down angle piece may need to be replaced, the end where it enters the discharge hose looks deformed from rust and deterioration.

I'm thinking that there's not enough coolant in the system which is the reason I asked.

Thanks for your quick reply. I can open one end of the heat exchanger and peek inside to see how dirty it is, but if the log is any indication, it should be clean, I'll check to make sure though before re-installing everything and refilling the H/E with coolant.

Mike
 
Mike, the pressure cap for a recovery system must have both seal surfaces.
**one to pressurize the H/E (at whatever pressure it is designed for)
**and one to seal the top so when the coolant temp returns to cold...... the Negative pressure builds and causes the coolant to be pulled back into the H/E.

Without this cap.... (or with a bad cap)...., the recovery system will not work!
The recovery hose connection must also be air tight! (this is a common area of failure also)


Your differential in exhaust manifold temperature can be from:
  • Clogged exahaust/riser water passages.
  • Un-equal division of spent sea water after it leaves the H/E (this is common).
  • If a diverter T fitting is used, these often DO NOT split the flow equally (also common).
  • Un-equal flow from two separate "spent" sea water ports on the H/E itself.
Much depends on the type of Sendure unit that you have.... and/or whether a splitter "T" fitting is used.

SJE had an issue with a run of brand new T fittings just a few years ago. They did correct the problem.
 
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I chased a problem (after getting tired with the mechanic who installed it saying..its all ok!) with the coolant level in the exchanger dropping but the level in the recovery staying high. I routed and rerouted the over flow hose. If I filled the HE and watched the engine warm up, I could see coolant leave the HE in the hose... but never go back when it cooled off. Changed the cap twice, same result.

On day I was sitting on the deck changing plugs and I sat up and looked at the cap and I took it off. I looked very carefully at the flange that the cap mates to and I noticed that the "rub" marks from the top cap seal to the flange did not go all the way around the flange. I put a straight edge on the flange and bent down to look at it and I discovered that the flange was bent ever so slightly causing the top seal in the cap to not "make" to the flange... vacuum leak!!!! On mine at least, there is a raised portion in the flange that the seal in the cap top is supposed to mate with and it wasn't the high spot 360 degrees around like it was supposed to be.

I got a hammer and a block of wood and gently tapped it "true" again (tapped on the outer rim of the flange which was raised). Problem solved! Level in HE is correct, level in Overflow goes up and down nicely.
 
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Bob, that's a good point to mention!
These H/E parts are soft and I suppose can be easily bent. So that too could be one of his issues!

.
 
Rick and Bob, thanks again for your inputs. I'm still in the tear down mode, and last night finished the other pair of riser/down angle pieces. It appears that the down angles on both sides are significantly blocked and rusted, those will be replaced. The Sendure unit I have is an L shaped model, with a large horizontal tube with access plates on both ends, and a vertical piece with the fill cap. I pulled the access plate on the raw water side, and found it to be relatively clean, all the rod ends exposed were open and did not appear to be clogged. I'll be ordering new down angles and risers tonight, with the appropriate gaskets, then relocating the recovery tank to a more appropriate location. Maybe by the weekend I'll have this one back up and running, and be able to report my progress, or lack thereof.

Rick, you through me off there with the Ricardo Marine entry in your profile, I should have known who you were immediately by my previous association with the BOC. Thanks for your recommendations, I do appreciate it.

Mike
 
mike33egg said:
.................
Rick, you through me off there with the Ricardo Marine entry in your profile, I should have known who you were immediately by my previous association with the BOC. Thanks for your recommendations, I do appreciate it.

Mike
Click to expand...
Rick who? :D

Mike, your guess was right on target!

Now, which Mike are you? I'm having trouble remembering!
(Must be an old age thing!) :rolleyes:
 
Rick, one of the many obsucre Mike's, I had a 1983 Contessa, and I may have asked about a weeping 290 outdrive at one time on the board. You responded with good information as always. Then I sold that boat for a more ambitious project, which I certainly have now.

Todays Update is this, replaced the risers and elbows on the port engine, reassembled everything and cranked her up. Immediately had an issue with the front of the log where the plate bolts up. Shut it down, removed the plate, found residue of the former gasket. Cleaned, removed same, thought I had it under control, attempted to restart, had the entire bank of cylinders hydrolocked. Out came the plugs, drained everything I could and attempted to find the souce of water, which was raw water at this point, not anfifreeze. After much hemming and hawing, I removed the log to see if there were any visible signs of cracking. I did not have a problem with this log prior to removing the the riser/elbow, except that it was very hot during 250 degrees during the original diagnosis. Anyway, noticed additional residual gasked material on the rear surface where the riser mates to the log. I'm hoping that is the source of the water infiltration at this point. I have cleaned that surface, will reinstall and try again. If I still have an issues, I'll assume that the new riser is the culprit and go get another. I'm told they can be bad out of the box.

So, that's my story, and I'm sticking to it at this point, unless I've missed something. Oh, no issue with the other bank of cylinders. Everything was drained and fogged too so hopefully I won't have any rust issues.
 
Just as a followup from my previous entry, the gasket residue which was not removed from the log end was indeed the culprit for the source of the water intrusion. Polished both ends of the log with the help of an angle grinder with an aggressive pad, replaced the unit on the block, new gaskets, reconnected the riser and elbow, and realized success. Engine runs fine, no hot spots, average temps at 140 or so. Now all that is left is to do the starboard engine.

Thanks for all of your inputs !
 
hello im looking for a thermostat housing for a 1978 chrysler 360 it was raw water cooled before but now with new engine i need a new therm. housing with two i guess 7/8 barbs instead of the 3 barbs that was with the rwc system that has rotted out. (see pics) the closest i found was a sendure 6743-2 it has 2 7/8 barbs like the one in the finished engine pic. but the bolt holes measure 3/58 center to center.surely someone knows where i can find the proper housing to complete my fwc cooling project.:confused::confused: downsized_1206111554.jpeg1209111258.jpg360_1977_pair11a[1].jpg360_1977_pair9a[1].jpg360_1977_pair7a[1].jpgthis is a pic of the type of sen dure heat exchanger i will be using...thanks for any help
 
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