Westerbeke W40 overheating under load

[Mickeyrouse]

This overheating sounds like our old 4-107. Did all the things the OP did, plus a few more. Ran muriatic acid through the raw water side of the heat exchanger. Changed raw water hoses. Thermostat- check. Water pump impeller- check.
What I finally did was have the heat exchanger acid soaked at a radiator shop. Turns out the problem was coolant build-up on the fresh water side. Re-installed the exchanger and the engine ran within specs forevermore. Finally replaced the engine after 33 years.

[lambrettaman]

Originally Posted by Poche

I was thinking that 190F isn't really all that hot, either. I don't know if anyone brought up checking the thermostat. A friend was sold the wrong one. Maybe try running without one and see what happens.

I just finished working on my cooling system on my 1981 MB diesel wagon. I agree, 190F is not that hot. It's in the upper end of the normal/ignore it range.

[moonmist]

Interesting posts. Not sure if this was addressed. Was the actual flow of the water pump">raw water pump verified? Most of these pumps operate at very close tolerances. A new impeller can not fix worn pump. A blockage from the air coming out of the engine can cause excess overheating in the cylinders. Exhaust connection on the W40 is 1 1/2" either end of exhaust manifold. Maybe back pressure not that bad ? Good luck nice boat

[Icarus]

Originally Posted by Dylancs

I’ve tried everything I can think of. The details-

1979 Westerbeke W40(Perkins 4-107) 2200 hours in a Niagara 35

Previous owner of 10 years proudly told me he never ran the engine above 1800rpm which he thought was a good idea so the engine has most likely been chronically under loaded for years. Surveyor fell in love with the boat during the survey and decided it was perfect so didn’t check basic things like batteries (all dry and ruined) or engine temp. I discovered the 90* raw water elbow at the exhaust elbow was almost completely blocked which tells me the engine had most likely been overheating for a long time.
Overheating under load above approximately 2000rpm. Temp increases with rpm increase.

Things done/replaced-
Raw water circuit cleaned out. New raw water pump. Oil cooler, heat exchanger, transmission cooler and v-drive cooler all checked. All new hoses. Exhaust elbow removed and checked for obstructions. Raw water intake increased in size from 1/2” to 1”.
Westerbeke states the exhaust should be 2” all the way back. Mine is 2” from exhaust elbow to muffler then 1.5” from there. The transom fitting is 1.5” and looks original from 1979 so this was the factory installation.

Fresh water circuit-
All hoses replaced.
I discovered this past week that the coolant pressure cap was rated at 4psi and Westerbeke says it should be 15psi. I pressure tested the 4psi cap and it couldn’t hold any pressure. Replaced with a 15psi cap and pressure tested the system. Pressure drops slightly then levels off for hours. Tightened all hose clamps. Tightened the fresh water pump/alternator belt.
Heat exchanger shows a 30F drop in temp between inlet and outlet of coolant circuit.
Water heater installed in system a few years ago. Originally I installed it in series as Westerbeke explicitly says to do. This does not work nor does it make sense. Now it is installed in parallel. Feed is from the coolant alarm sender port on the head which is reduced from 1/2npt to 1/8npt to reduce flow to the water heater and return is to the heat exchanger. There is a shutoff valve in the feed line so I can remove the water heater from the circuit for testing purposes and it doesn’t seem to make any difference.

Air filter was cleaned out. Sea strainer has been cleaned repeatedly. I’m at a complete loss. Nothing I do seems to make any difference. Temperature is being taken at the thermostat (also replaced) with an infrared temp sensor as well as the engine sensor (also replaced).

Sorry for the long post but this has been 3 years of dealing with this and I’m desperate. I’ve been told the cooling system on these engines is marginal to begin with so I’m not expecting perfection. I realize there are many, many reasons for an engine to overheat but I feel like I’ve exhausted most of the possibilities. Any help would be greatly appreciated.

Dylan

Looks like the heat exchanger is to small or the raw cooling water flow is insufficient.
Can you change the pump drive pulley to a smaller one? This would increase the cooling water flow to the heat exchanger.
I would probably look at getting a larger heat exchanger.

How good is the fresh water circulating pump?

When is the last time the cylinder head has been refurbished/pressure tested for a possible leak?

[Dylancs]

I’ve decided to replace the exhaust. 1.5” is definitely too small. Now the question is what size? Off of the engine it’s 2”. Westerbeke suggests in the install manual 1 7/8” or 2” all the way back. Centek, one of the large exhaust component manufactures suggests 2.5” for diesels up to 40hp. Vetus suggests 2” up to 40hp. My current muffler is a Centek 2” in and 1.5” out. I can get a Vetus waterlock 2” muffler off the shelf locally. I read that no wet exhaust hose connections should be made at anything other than a solid fitting which includes the engine exhaust elbow, muffler or thru hull. This seems to negate using a 2.5” to 2” reducer.
I have found a place across the border from me that makes marine exhaust components. I can have a 2” to 2.5” fibreglass muffler made for a somewhat reasonable price but still significantly more than the stock Vetus. My issue is that I’m a pilot and therefor currently unemployed. I’d prefer to not spend money that isn’t necessary. Obviously my boat doesn’t care about this. I just bought a new $1000 raw water pump a few weeks ago...
I’m willing to spend the extra money if it’s necessary. What do other have with their W40’s or 4-107’s?

[Dylancs]

Originally Posted by Mickeyrouse

This overheating sounds like our old 4-107. Did all the things the OP did, plus a few more. Ran muriatic acid through the raw water side of the heat exchanger. Changed raw water hoses. Thermostat- check. Water pump impeller- check.
What I finally did was have the heat exchanger acid soaked at a radiator shop. Turns out the problem was coolant build-up on the fresh water side. Re-installed the exchanger and the engine ran within specs forevermore. Finally replaced the engine after 33 years.

I read an article by Steve D’Antonio about something similar I think. He said it was a not-too-common problem with heat exchangers where they can form a film on the fresh water inlet which prevents full flow. I had my HE professionally cleaned at a radiator shop a couple of years ago. It didn’t seem to make any difference to the overheating issue. I have opened the end of the heat exchanger several times since to make sure it’s clear and to clean it out if it isn’t.

[Dylancs]

Originally Posted by lambrettaman

I just finished working on my cooling system on my 1981 MB diesel wagon. I agree, 190F is not that hot. It's in the upper end of the normal/ignore it range.

Westerbeke says 190F is the maximum the engine should run at. Mine runs significantly hotter than that if I let it. As I’ve said in a previous post, the hottest I’ve let it get when testing was 210F at 3000rpm and the temp was still increasing. When my tachometer wasn’t working recently I realized that I could set the appropriate rpm by the coolant temp. 1800rpm is currently about 190F. 2000rpm is about 195-198F. 2200rpm is about 205F, etc. This hasn’t been consistent over my 3 years of ownership but it’s pretty close.

[Mickeyrouse]

After my HeatXchgr boil-out the engine would run under load at about 185. A friend with a similar engine ran his constantly above 220, but he didn’t worry because he ran with pure coolant. When I sailed with him, I was always antsy about the cockpit seat over the engine.

[MVDarlin]

I have a 4.5 kw Westerbeke gen set. I had am overheat problem when I first bought the boat. I checked the raw water impeller and found a blade broken. But I did not find the impeller blade so I checked the hose to the heat exchanger and pulled the cap. I found 7 impeller blades inside. Seems this was a problem for the prior owner. I used a welding rod to clean out the heat exchanger and it has run well since.

[Dylancs]

I have ordered all the parts for the new exhaust and they should be showing up in a week or two. I’m going with 2” all the way. I also removed the heat exchanger and oil cooler and put them in a bath of Barnacle Buster. I noticed that the fresh water side of the HE tubes had a black film on them which is what I had read about in this article.
https://www.cruisingworld.com/how/en...g-system-tips/
I also removed the Groco raw water strainer and I have cleaned that and ordered a rebuild kit which should show up in the next few days.

Thanks again for all the tips and suggestions. I’ll give an update for those interested once it’s back together.

Dylan

[Dylancs]

And the saga continues. I put the HE and the oil cooler back on today. I have obviously already drained all the coolant and bought new stuff. When I was dumping out the coolant in the expansion tank I noticed some black sludge in it. It looks like the same stuff that was costing the coolant side of the HE tubes.
When I bought the boat and had the HE boiled, I also changed the coolant. It had been green and I went with red. I made sure to completely flush out the system until the water was running clear. About a year later, with the engine still overheating, I decided to pull off the 90* fitting where the raw water was going into the exhaust elbow. It was almost completely block with what looked like salt deposits. I cleaned it out which resolved the white steam coming from the exhaust but didn’t cure the overheating problem. What I think happened was that the engine had been overheating for the year between cleaning the HE and finding the blockage. Aside from all the other issues that I’ve been fixing, I think this caused the black sludge to accumulate in the fresh water system. So now I need to completely clean out the fresh water system and try to remove the black sludge.

Does anyone know of any products to do this properly? There are a lot of opinions online but I’m wondering if anyone has actually done it successfully.

[Sailor647]

Any idea what is causing the "black sludge"? Oil from head gasket leak?


Have not had to flush our antifreeze side, so can't give you any firsthand advice on that. Sorry.



Interest to see how you finally solve this...


Best of luck.

[Dylancs]

I pressure tested the coolant system a few weeks ago and after a slight drop in pressure it maintained the required pressure for many hours. I don’t think this is a guarantee that the head gasket is intact but hopefully a good indication that it is. From what I’ve read, the black film can be from the engine overheating and then the coolant not being replaced as per the article I linked in a previous reply.
https://www.cruisingworld.com/how/en...g-system-tips/

I bought some Kleen Flo 10 minute rad flush yesterday. It was recommended to me by a marine diesel mechanic. He said it’s what he uses. I’ve bought many gallons of distilled water to flush out the system as well. I’m going to be running this through the system today and I’ll see what comes out. Might have to do it a couple of times.

I have the new exhaust hose and the muffler should be showing up in a day or two. The new transom tail piece is still stuck in Miami so I’m not sure when I’ll be able to replace the exhaust. I’ve also discovered that the Groco raw water strainer I have is also too small. It has 1/2” ports and is supposed to be a minimum of 3/4”. So I’ll be replacing that at some point this off season as well...

[Dylancs]

Another update. I used the coolant flush today. It took a long time and a lot of flushing with fresh water to clear the system. This, along with the heat exchanger cleaning seems to have cured the overheating problem. I need to do some more testing tomorrow but I was able to run the engine up to 2500rpm today without issues. So that’s the good news.

Now the potentially bad news. When I started the engine up to run the coolant flush through for the 10 mins required, I noticed a cloudy and somewhat brown looking substance in the water from the exhaust. Almost like some particulate coming out and creating a cloudy substance in the water. It was consistent for the full 10 mins. I assumed it was the residual effects of the barnacle buster and would flush itself out. I had to run the engine a few times while flushing it and the exhaust discharge was the same. It’s possible that this has been happening for a few weeks and I only noticed it now but I can’t be sure.
Just to recap, I put the oil cooler (only the raw water side), heat exchanger and raw water strainer in the barnacle buster bath. When I ran the engine with only clear water, the discharge was the same so I assume it’s not coolant. There isn’t an oily sheen on the water. I’m going to get a sample of the water from the exhaust and the anti syphon valve discharge in a bucket tomorrow. The water from the anti syphon valve is from just prior to the exhaust mixing elbow so I’ll be able to see if there’s a difference between the raw water before and after the exhaust elbow.

Does this sound familiar to anyone? A blown head gasket is what I’m most concerned about but I’m hoping it’s either nothing or something more simple.

[Dylancs]

To close this thread, the overheating issue seems to have been solved. It looks like it was the result of previous overheating caused by a blocked 90* fitting where the raw water is injected into the mixing elbow. Judging by how blocked it was, I can only assume it had been restricted for quite some time. I didn’t find it until about a year after I bought the boat. Even though I had changed the coolant several times over the past 3.5 years, it had obviously been contaminated by overheating due to various other issues, such as the incorrect (Westerbeke’s recommendation) plumbing of the water heater and the undersized raw water intake, raw water strainer and exhaust.

The fresh water side of the cooling system became contaminated with a black film as was shown in the article I linked in a previous post. The black film acted as an insulator thereby preventing the exchange of heat.
It’s possible that the engine has suffered some damage over the years from the improperly sized raw water intake (1/2”), strainer (1/2”) and exhaust (1.5”). And also from the previous owner never loading the engine beyond 1800rpm as he claimed. Time will tell. I increased the size of the raw water intake last year to 1”. I’ll be replacing the strainer and exhaust when the parts show up.

Thanks for all the advice and ideas. Hopefully this can help someone else with a similar problem.