Westerbeke W40 overheating under load

[Scubaseas]

Regarding being over-propped, I can achieve the rated 3000rpm

You are not over pitched if you can reach 3000 RPM.

You can apply vacuum to the expansion tank to rule out air pockets in the cooling system. Search vacuum fill cooling systems. You need about 16" to 18" vacuum for this to work but it sounds like you are fine in this department. Given the amount of coolers I suspect the original HE is undersized for the job. BUT I would still check the raw water flow rate at water pump">raw water pump outlet versus the flow at the elbow and the exhaust itself.

[Cheechako]

Originally Posted by Dylancs

Thanks for all the good info. Regarding being over-propped, I can achieve the rated 3000rpm but I’m not certain this is an adequate indication. In fact it’s almost exactly 3000rpm at full throttle. I was told by a local marine diesel mechanic that these engines are known to have marginal heat exchangers, as others have said, so this could definitely be the culprit.
I’ve been thinking for a while now that I was getting air into the coolant system but now that I’ve pressure tested it and tightened all the connections that seems to be eliminated. I have tried running the engine with the coolant cap off but the vibration of the engine simply causes a lot of coolant to slosh out.
The previous owner’s comment about not running the engine above 1800rpm was simply his complete lack of knowledge about boats in general. He initially told me that the engine had “a lot of hours on it, like around 3000”. He then checked and it was 1800. To give some more context, after 10 years of ownership he didn’t know there was a holding tank pump out which was right next to the thru-hulls for the toilet. The benefit of his lack of knowledge was that he had professionals do all the work required. Unfortunately it also meant he never bothered to check engine parameters. Had the surveyor done his job properly and had I been looking as well, we would have seen the engine was overheating under load during the sea trial and this could have been resolved during the purchase 3 years ago. Live and learn.

My oil cooler is already directly after the raw water pump. The circuit is- 1” intake, Groco raw water strainer, 3/4” hose to raw water pump, 5/8” hose to oil cooler, 5/8” to HE, 3/4” to transmission cooler, 3/4” to V-Drive cooler, 3/4” to anti syphon, 3/4” to exhaust elbow.

I’ll add a photo of the engine later today when I’m at the boat in case there are any obvious visual clues that I’m missing.

Here's a thought... can you bypass the oil cooler temporarily? Or just put a valve in the hose (if there is a hose... not pipe) Then close the valve and see if the engine still overheats. My 4-108 didn't have an oil cooler at all.

[jimbunyard]

Originally Posted by DougR

Jim, Your understanding of overpropping is correct....

The max pleasure rating of the 4-108 was 50 hp @4000 rpm.

Perhaps I didn’t take my propping comments far enough...I propped my engine so that at WOT I could only achieve 3700 rpm (slightly over wheeled). I normally cruised at 2700rpm, but could cruise at 3200 if necessary. Anything more than 3200 didn’t achieve an increase in speed because the boat was already at hull speed and anything above 3200 just squatted the stern and made black smoke.

The point that I was trying to make was that even with the engine somewhat over propped, with a proper sized HE installed my 4-108 engine temp was controllable at any engine speed.

Thanks for the clarification, was operating under the impression that the max rpm was quite a bit less...

Originally Posted by Dylancs

Thanks for all the good info. Regarding being over-propped, I can achieve the rated 3000rpm but I’m not certain this is an adequate indication. In fact it’s almost exactly 3000rpm at full throttle. I was told by a local marine diesel mechanic that these engines are known to have marginal heat exchangers, as others have said, so this could definitely be the culprit.
I’ve been thinking for a while now that I was getting air into the coolant system but now that I’ve pressure tested it and tightened all the connections that seems to be eliminated. I have tried running the engine with the coolant cap off but the vibration of the engine simply causes a lot of coolant to slosh out.
The previous owner’s comment about not running the engine above 1800rpm was simply his complete lack of knowledge about boats in general. He initially told me that the engine had “a lot of hours on it, like around 3000”. He then checked and it was 1800. To give some more context, after 10 years of ownership he didn’t know there was a holding tank pump out which was right next to the thru-hulls for the toilet. The benefit of his lack of knowledge was that he had professionals do all the work required. Unfortunately it also meant he never bothered to check engine parameters. Had the surveyor done his job properly and had I been looking as well, we would have seen the engine was overheating under load during the sea trial and this could have been resolved during the purchase 3 years ago. Live and learn.

My oil cooler is already directly after the raw water pump. The circuit is- 1” intake, Groco raw water strainer, 3/4” hose to raw water pump, 5/8” hose to oil cooler, 5/8” to HE, 3/4” to transmission cooler, 3/4” to V-Drive cooler, 3/4” to anti syphon, 3/4” to exhaust elbow.

I’ll add a photo of the engine later today when I’m at the boat in case there are any obvious visual clues that I’m missing.

As seems to be the general consensus, I'll wager that the problem is a result of the combination of several factors; a somewhat undersized heat exchanger, a relatively heavy boat, some degree of overpropping, and likely exhaust restriction.

The solution will probably be some combination of remedies; perhaps the cost aspect may be the most pertinent metric; pretty sure if you drop a couple inches of pitch, install the 12" heat exchanger, and open the exhaust to the rated 2", your problem will disappear.

It may require all three, or maybe just one will do the trick.

Is the overheating relatively linear from 2000 to 3000 rpm? If so, that would seem to indicate a design problem, not a fault (air locks, thermostats, obstructions, etc.).

Given the changes you've already tried, my approach would be simply cost-based; depending on circumstances, probably increasing exhaust size first, then decreasing prop pitch (contrary to popular belief, just because your engine can reach rated rpm doesn't mean in every circumstance that your prop size is correct; these are dynamic systems), and finally going to the larger H/E.

An analysis of your current speed as well as your potentially attainable and desired speed, as explained by Doug above, might be a good starting point in determining if a prop change would be beneficial.

I've had several instances of engines, in otherwise good shape, capable of reaching rated rpm, but nonetheless overheating, generally in direct proportion to how overpropped they were; i.e. the less overpropped, the slower the temperature rise was, and vice versa. Only when they were severely overpropped did they fail to reach rated rpm.

Granted, this is not very common, but it does happen with some regularity, though perhaps more frequently on planing hulls.


Perhaps it should be kept in mind that the 3000 rpm the Westerbeke rating carries is for commercial service; the pleasure duty rating is 3600 or 4000.

[Poche]

[QUOTE=Sailor647;

We clean (boil it out with muratic acid) the heat exchanger annually and also removed the zinc which just plugs it up faster.

Best of luck.[/QUOTE]

How do you know the zinc plugged it up faster? Just asking because I plan to check and probably replace mine soon. I'm not overheating. It seems like good maintenance.

[Mr B]

I have a B30, It was missing two blades on the inlet water pump,
It overheated chronically,
Replaced the impellor, Its been 170 F since,
Old motor, It may have blades missing or corroded to nothing in the motor, Fresh water pump,
Is yours a Mitsubishi engine, Marineised by Westerbeke,
Buy your parts from a Mitsubishi car parts dealer,

[Poche]

Originally Posted by Mr B

Its been 170 F since,

Interesting. Never heard of a Mitsubishi converted by Westerbeke. Anyway, I have a W40 that runs 170F at load around 1800 rpm. Checked by IR. Hottest spot I could find.

[Mr B]

Originally Posted by Poche

Interesting. Never heard of a Mitsubishi converted by Westerbeke. Anyway, I have a W40 that runs 170F at load around 1800 rpm. Checked by IR. Hottest spot I could find.

Westerbeke dont make engines, They only marinise them,

The Westerbeke B30, Is a Mitsubishi diesel motor,

Your W40 will be an engine from some manufacturer,
It will have a label on it some where stating which company built the engine,

[sailah]

Originally Posted by Poche

Interesting. Never heard of a Mitsubishi converted by Westerbeke. Anyway, I have a W40 that runs 170F at load around 1800 rpm. Checked by IR. Hottest spot I could find.

Lots of Westerbekes are marinized Mitsubishi blocks. My 44B is a Mistubishi S4L2 block. The factory Mits service manual is miles ahead of anything from Westerbeke who still insist on scanned pencil drawings vs Acrobat docs that you can search from Mits.

[Sailor647]

Originally Posted by Poche

How do you know the zinc plugged it up faster? Just asking because I plan to check and probably replace mine soon. I'm not overheating. It seems like good maintenance.

Since we clean the heat exchanger every year, we could see the difference - literally small pieces of anode in the tubes and at the bottom of the bucket we used to clean the HE out. Since the engine is connected to the bonding system in numerous other places, it's still protected.

[Sailor647]

Originally Posted by Mr B

Westerbeke dont make engines, They only marinise them,

The Westerbeke B30, Is a Mitsubishi diesel motor,

Your W40 will be an engine from some manufacturer,
It will have a label on it some where stating which company built the engine,

No it won't. lol Westebeke makes sure to remove any numbers that would help you identify it and find cheaper parts.

[Mr B]

Originally Posted by Sailor647

No it won't. lol Westebeke makes sure to remove any numbers that would help you identify it and find cheaper parts.

Exactly,
My Genuine Original Westerbeke Alternator got submerged and was totally rusted out inside,
Missing bits as well,
New one was around $400-00 USD plus postage, Ouch, From Westerbeke,

Im in Australia, Whats Westerbeke, Never heard of it,
From the car alternator repair company,

I took my Alternater in to have it repaired or get a new one or get some thing similar to put on my boat,
One off a Diesel car, Etc Etc, I dont care what its off, As long as it works on my boats diesel engine,

Wow, This is a real old one, I dont know if I have parts for it, Its certainly cactus inside,
Its definately a Mitsubishi Alternator, You will have to leave it with us for a few days,
3 days later, I get a phone call, Your Alternator is fully repaired, I found some old parts on the shelf,

$130-00 Total cost, Full rebuild of my Mitsubishi alternator, Its on my boat and works great, And has done for the last 1000 Nmiles,
Mostly on the motor as there was no wind,

Gemini Cats have about 1200 Westerbeke B30's in them,
Rebuild the motor straight out of the Mitsubishi car parts dealership for a quarter of the price of Westerbeke parts,

[Dylancs]

Thanks again for all the helpful suggestions. I’m currently out on the boat for a couple of weeks with limited internet. My HE is stock but not the original. It’s a Westerbeke 14129CN. It’s 3” x 15”. Maybe Westerbeke put larger HE’s on the W40 than was stock on the Perkins 4-107?
I was hoping that changing the coolant pressure cap from 0psi to 15psi would make a difference. Nothing. At least there’s protecting from premature boiling.

I’m currently running the engine and now I’m at 190F at 1800RPM. The overheating is proportional to engine rpm. It seems like the more I try it fix, the worse it gets. The only consistent solution I’ve found is to not run the engine at all. Works like a charm every time. It really does not seem to matter what I do, it runs hot. I’m going to have to look at replacing the exhaust. I’m going to pull the exhaust apart to see if there are any obstructions in it. There is good flow coming out but it seems like it pressurized when it comes out. More of a spray. I’ll check that when I get to my destination today. Maybe some creature crawled up there and died.
Then I’ll look at bypassing various coolers to see if that makes a difference and go from there.

[er9]

Originally Posted by Poche

How do you know the zinc plugged it up faster? Just asking because I plan to check and probably replace mine soon. I'm not overheating. It seems like good maintenance.

it uses a pretty big zinc and they quickly break up into large chunks that clog that section of the heat exchanger. iv'e taken to chopping mine down to a small nub and replacing more often.

[DougR]

OK...so your HE should be adequate size.

Seems to me that your delta T of 30 degrees on the HE should be plenty to cool the engine......if you have enough coolant flow thru the HE. Low coolant flow will result in good delta T, but won’t cool the engine.

You don’t say whether you have checked the thermostat for functionality...

[Mr B]

Originally Posted by Dylancs

Thanks again for all the helpful suggestions. I’m currently out on the boat for a couple of weeks with limited internet. My HE is stock but not the original. It’s a Westerbeke 14129CN. It’s 3” x 15”. Maybe Westerbeke put larger HE’s on the W40 than was stock on the Perkins 4-107?
I was hoping that changing the coolant pressure cap from 0psi to 15psi would make a difference. Nothing. At least there’s protecting from premature boiling.

I’m currently running the engine and now I’m at 190F at 1800RPM. The overheating is proportional to engine rpm. It seems like the more I try it fix, the worse it gets. The only consistent solution I’ve found is to not run the engine at all. Works like a charm every time. It really does not seem to matter what I do, it runs hot. I’m going to have to look at replacing the exhaust. I’m going to pull the exhaust apart to see if there are any obstructions in it. There is good flow coming out but it seems like it pressurized when it comes out. More of a spray. I’ll check that when I get to my destination today. Maybe some creature crawled up there and died.
Then I’ll look at bypassing various coolers to see if that makes a difference and go from there.

The ID of your brass fittings seems very small, and restrictive,,
Every time the water goes thru a fitting it would cut the flow down a bit,
That may be the cause of your over heating,

The big hose going in and the small hose coming out would pressurise your system also,

Welding in bigger sockets would fix the problem, Local welding shop can do that for you,