Dreaded Universal 5432 running hot syndrome [Master Thread]

[rwthomas1]

Hello All,
I never motor very far, maybe a half hour or so at a time so I never really work the Universal 5432 in my E38 very hard or long. Well, I had to motor for about 1.5hrs on Monday to get where I was going and the engine ran pretty hot. Normally I don't run much above 2200rpm as I don't have to. This time I was running against a current and had to push her to 2600rpm to make any decent headway. After about a half hour the temp gauge was showing 200*F. I backed down to 2000rpm and the temp dropped to maybe 180*F. I pushed back to 2200rpm and the temp popped back up to 200*F. I kept an eagle eye on the gauge and ran like this. Running at 200*F is no big deal in the short term, I know this from automotive experience however I know that its not right and needs to be fixed. There was a bit of steam coming from the exhaust but there was plenty of water pumping out.

Today I disassembled the cooling system. The raw water pump is fine, impeller is in perfect shape. Removed all the raw water and coolant hoses, no obstructions. Removed heat exchanger and it too was clean, no buildup at all, its a 3" round unit. The exhaust elbow was replaced by the PO, its a new Westerbeke stamped unit. The rest of the exhaust hose looks very recent.

The one thing that was not "correct" is the water heater was tied into the cooling system inline not in the bypass line as suggested in the threads I searched for info. I have reinstalled most of the hardware but I need to source some 1/2" marine water/exhaust hose to run the water heater line to complete the modification.

Questions:
1. Do I need marine water/exhaust grade hose to run to the water heater or will automotive heater hose do the job? Its just a coolant hose after all.
2. For the people that have performed the "bypass hose" modification to a 5432, did it work long term to control engine temps?
3. Does the smaller hose produce ample heating for the water heater?

Thanks, RT

 

[Steve]

Just a thought

Did you look at the thermostat? Perhaps it isn't opening fully.... My 5424 ran too cool due a thermostat not closing... 140 - 150 all day after a long warm up!

Steve

 

[wheelerwbrian]

Do the hot water heater bypass first -- it will be cheaper -- but then you might want to look at the raw water pump. If you have an Oberdorfer, it pumps about 3.2 gallons per minute. The Sherwood pumps about twice that amount. Its an easy swap out, but pricier than hose.

The OME cooling system on the 5432 is the same capacity as that used on smaller Universals, and has insufficient reserve in my opinion.

 

[Shadowfax]

Other Things to Check

I like the thermostat advice and would certainly try that. Some times the cap is bad and will not hold pressure, but I doubt that is the problem.

You say you infrequently run the engine and then for short periods. If none of the other stuff works, or as you go through the check list, remove the hose that feeds the riser and check for carbon goop buildup. Remove the fitting the hose attaches to and run a screw driver around in there. You won’t hurt anything and if you have a buildup it will break it loose. When you start the engine you should get a lot of carbon, in liquid form, if this was the problem. I had happen to me once. If this, or the thermostat, etc., is not the problem, I’d begin to suspect the engine water pump, especially if it has not been replaced in 10 years

 

[ted_reshetiloff]

I have done all the things mentioned excepting the sherwood pump and replacing the fresh water pump on my 5432 and have the same problem. It will run at 185-190 all day at 2000. Anything above that and the temps start creeping up towards 200. I am going to try using a heat exchanger from an m50 to see if it will help. Perhaps a bigger heat exchanger in conjunction with the Sherwood pump and the temps will stay down. I can't figure it out as the cooling system is spotless. No corrosion or plugged passages. When I set the valves the rocker assy was spotless too with very little signs of wear. I dont have an hour guage but I am beginning to thik my motor has lower hours than I initially thought.

 

[wurzner]

Ted,

Sorry for going silent, had a race last weekend and had to high tail it home for a quick shot to the airport (concerned about long lines). I was off line for a while. I took the heat exchanger apart this morning and can send you photos. I don't know what I did with your email address.

Please send it to me back channel and I'll get the photos over. The exchanger looks really good. If you don't want it, send it back and we can split the shipping.

regards
shaun

 

[Emerald]

Hi,

regarding the heater hose question, a couple things to mull over. Generally speaking, automotive grade heater hose is apt to have carbon black in it, and marine grade hose is made with silicone rubber. I believe the idea behind this is the silicone rubber doesn't introduce a corrosion or electrolysis issue into the equation. This is probably more of an issue using hose with carbon black on bronze thru-hulls versus attaching to an iron engine, but that said, if you check someone like Shields, you'll find they're using silicone rubber:

http://www.shieldshose.com/shields/prod/hoses/engine_hose.html

for some interesting reading on "industrial rubber", check this out:

http://www.cabot-corp.com/cws/businesses.nsf/CWSID/cwsBUS02062001112557AM2316?OpenDocument

The other things to keep in mind is that any hose under suction or pressure in your cooling system should be reinforced to resist collapse or expansion per the application.


I would add not to go too nuts on rubber types, as I've certainly seen a lot of automotive grade heater hose in marine applications, but if I were starting clean on a new project....


-David
Independence 31
Emerald

 

[rwthomas1]

Hello All,
Thanks for the suggestions:
-I already have the Sherwood raw water pump.
-The exhaust elbow is new and the water injection fitting into the exhaust is clear.
-Ordered a new thermostat today.
-Did the bypass modification today, used Shields marine heater hose. Its black but marine rated, and specifically designed for the application.

I will be testing the setup in a day or so. The engine runs well but has plenty of hours on it. Will also replace the pressure cap.

Ted, have you considered that maybe your temp gauge is incorrect? Sounds dumb but sometimes its the easy stuff.....

RT

 

[hodo]

Rob, check and see if you have a check or "flapper" valve in the exaust. I have seen those come apart andcause overheat problems. good luck, let us know what you find. Harold, S/V Mischief Maker

 

[rwthomas1]

Update:
The coolant pump is new. I ran the boat today for about a 1/2hr at 2500rpm and it still heats up. Not as hot as before, maybe peaking at 190*F-200*F about a needle width less. It also cooled off to 160*F once I cut power to below 200rpm. It never did that before.

Regarding the "flapper" in the exhaust system, where exactly is it? I have not seen any location where something like this would be. Location?

Thanks, RT

 

[hodo]

Rob, the flapper valve is usually installed between the exhaust elbow and the waterlift muffler. You will see what looks like a bronze (probably green) pipe coupling with a hex or square cap on it. about 3" long, in the rubber exhaust hose. While you are looking, check carefully for cracks or separations in the covering of the hose. Good Luck, Harold

 

[Shadowfax]

Dirty Bottom?

Could it be something as sinple as your bottom and prop are very dirty forcing the engine to work harder and run hotter. This just happened to a friend of mine. Just a thought.

 

[wurzner]

I think everyone here is bringing up very good points, but I also think you are all missing a very fundamental thing. The heat exchanger is undersized and most likely, those of you who are not experiancing overheating have a larger heat exchanger from a PO. It is likely that when everything was brand new and 100% efficient (or operating to new specifications), it would work. Ted is going to try out my old heat exchanger from my blown engine and I ensure you the over heating issue will be a thing of the past. Measure you heat exchanger and if it is 2.5 x11, it is the standard one and if it is 3 x 13 (approx), it is the ugraded one.

Shaun

 

[rwthomas1]

Exterior dimensions of the heat exchanger is at least 3" diameter. It surely is not the small one. The bottom of the boat has some "fuzz" on it but no hard growth. The prop has a bit too, but motoring for a while knocked a lot off. The thermostat is next. RT

 

[ligolaiva38]

RE: e-38 running hot

Hello,
My 1984 E-38 never ran over 160 degrees and I was developing soot buildup etc. in the engine which was getting dangerous for the engine and hard to start at times--not to mention lots of soot on the stern.
With time I finally removed the original old Raritan water heater and replaced it with a Isotherm 8 gal. water heater. The engine heat immediately jumped up exactly like Rob Thomas' description. I checked with my diesel expert and he said it was not bad and it would clean out all the build up in my engine from previous years of running too cool. He stated diesels like running "hot and hard". Another tip he gave me was to never turn off the engine when it is running hot above 180 degrees like sailors frequently do when motoring and the wind comes up and they begin sailing.
Sure enough, the stern had much less soot build up, and after a while it started much quicker and easier. It even sounds better now when it is running. I run it at 2400 rpm and in the summer when the water is around 70 degrees the engine runs between 190 and 200 degrees. At 210 degrees the beeper starts very mildly buzzing.
I once met an E-38 owner at Catalina Island who had done serious cruising and had over 5000 hrs on his Universal 5432 and he said his engine always ran at 200degrees. So I think that it is more damaging for a diesel engine to run cool than hot since so may folks have rebuilt their engines under 2000 hrs of running.
What I also did was put in a bypass valve that opens up a direct route bypassing the water heater and another valve in the line to the water heater to close water entry so the water would circulate more directly and quicker by bypassing the water heater.
If I have to really push the engine hard in real hot water and it gets over 200 degrees or when the heat exchanger starts building up crap inside it and has some blockage I can bypass the water heater and cool off the engine.
When running in So Cal during summer months especially during red tide there is a greater chance of build up of burned algea etc inside which clogs up the inside of the exchanger because there is so much growth in the water.
I was told that in So CAL one should boil out the heat exchanger every 3-4 years. That is about when my engine starts running hot and I have the heat exchanger boiled out.
John
Laiva E-38

 

[wurzner]

John,

I agree with you. My new engine runs at 160 just like my old engine and I'd be a lot happier with it in the 170~180 range. 160 seems too cold but that is how they engineered it. Everything I've ever read says 160 is too cold. The only issue being, the system should sustain that temperature even when pushing the engine.

shaun

 

[Emerald]

Ideally, an engine is probably happiest running in the 180-200 F range (200 really is tops though, 195 better as an upper end). The trade off in the marine environment is that if you run sea water coolant at these temperatures, you end up having a much greater problem with percipitants (read salt etc.) coming out of the cooling water and clogging/corroding things, hence the tendancy to run marine engines on the cool side like 160 or even less.

If you are fresh water cooled with a heat exchanger, you should be able to operate safely in the 180-200 range. Also remember to a limited point, some of this is relevant to the specific engine only. What I mean is if you have an engine that is running happily all day at 200 and never misses a beat, don't worry about it. Worry when all of a sudden it's running at 210 one day - that sudden change will be the tip something is wrong. This applies to any baseline running temperature. If it's always done 155, it's the day it jumps to 180 to start looking for a developing problem.


-David
Independence 31
Emerald

 

[ted_reshetiloff]

The 5432 is freshwater cooled and the manuals say it should run at 190. I would think 200 is getting pretty hot, given the t-stats on these guys open at 160. If you are concerned about one running too cool get a different t-stat. You can probably get a 170 degree tstat.

 

[Emerald]

Yes, by all means follow the temperature specification for the engine. I should have prefaced my prior post with it being a very general guideline on engines in general. Also, some of what I should have mentioned is that part of why the exact number on a particular system is not as important as what the normal operating temperatures are and deviation from those temperatures, is that errors caused by age, corrosion etc. in gauges, sensors, wires etc. may all add up to show a reading that is not truly dead on, so the engine that always showed itself to run a little hot, but seemed to operate flawlessly and didn't increase temperature under heavy load may very well be just fine, and it's some other thing showing a reading that is slightly off and misleading.


Did that make sense? Hope so.


-David
Independence 31
Emerald

 

[CaptnNero]

what guage ?

Ahem, ah, ...Dare I say that I have even heard of some boat engines around which do not have a temperature guage ? May the powers that be have mercy on their poor unfortunate souls...