Overheating

[ctjstr]

I hope to figure this out on Thursday when I get a chance to get some stuff done, but any suggestions would be appreciated.

About 3 months ago I started noticing the engine getting a bit warm as I ran it much over 2500 rpm. Not a big deal but something to check on when I had a moment

A short time later, I had reason to go though all 4 coolers on our Volvo tamd41, replacing the oil cooler and thoroughly cleaning the other 3.
ever since, teh heating issue has not gotten better. In fact, its gradually worsening. I replaced the impeller, checked the water intake strainer and checked the two thermostats. No love there.

I'll try and run it down more thursday by checking that the water intake through the hull is clear and trying to spot the hot spots with a temp gun.

Any other thoughts/suggestions?

thanks

toni

 

[Durant F]

Make sure the exhaust mixing elbow is totally clear.
Often overlooked, but important.
Then the normals... water pick up cage clear?
Thermostat working correctly?
Coolant right level etc..

 

[Comodave]

Make sure the exhaust mixing elbow is totally clear.
Often overlooked, but important.

+1

 

[Arc]

Did you ever break an impeller? Those blades turn up in the darned places

 

[Lepke]

Have you done a flush on the coolant side? Rust can build in the coolant passages and act as insulation, keeping the coolant from absorbing all the heat. I fixed a lot of overheat problems after others changed pumps, thermostats and exchangers without ever cleaning the coolant side. It's like a car, needs to be done every few years. Most just do the salt water side because it's obvious.

 

[O C Diver]

Check your propellers. Growth such as barnacles can reduce the efficiency (increase the load) on the propeller to turn at the same RPM. This increased load requires more fuel, which generates more heat for the same RPM. While this may not be the only problem, it can exacerbate other problems.

Ted

 

[Maerin]

To what's already been mentioned, add a check of the condition of the seawater pump. A worn wear plate and/or cam can really reduce the flow rate of a pump, and it's not clearly evident without accurately determining the flow, not an easy task. Just keep an eye out for that wear, since it's cumulative and the flow can fall off incrementally with no symptoms until one day it's just not enough. A justification for maintenance based on hours. Add any other shortcoming and now you've got an overheat issue.

 

[Ski in NC]

Get up to the power level where engine temp starts climbing. With IR gun check temp of wet exhaust at muffler or FG pipe well downstream of where water is injected, to get good mixing. Most marine diesels the wet exhaust is about 20-30F above sea water temp. Get 50F plus above SWT and you have low sea water flow. If 20F delta and engine still getting hot, SW flow likely ok and you have an issue on the coolant side.

Heavy steam out the tailpipe is a hint you have low SW flow, but not a conclusive check there. Weather can cause steam too.

 

[sunchaser]

Seems like a pretty thorough go through on your part plus some very good suggestions. Add to the list bad coolant pump and plugged after cooler (if it has one).

 

[Trawler Sandpiper]

I wonder if a coolant hose might be collapsing due to corrosion of the inner spring. Give them a little squeeze and listen / feel for any crunch. Had this happen on my Lehman.

 

[twistedtree]

When you say you went through the 4 coolers, which coolers and exactly what did you do? Obviously something has been missed, so its about going back through with a fine tooth comb, measuring temp drops as ski describes, etc.

 

[ctjstr]

thanks for all the suggestions to add to my list.
what I did so far on the coolers is replace the oil cooler, and then remove and clean the rest; aftercooler, transmission cooler and heat exchanger. Heat exchanger was disassembled and the tubes cleaned. aftercooler was disassembled and the insert cleaned, although I left the housing in place. I'm relatively confident that the issue is not in the coolers.

No idea if the impeller ever lost blades, but not since I've had it. Old one was fine and the new one is...new. I did not spot any pieces when I took the coolers out and cleaned them.

I will check the status of the exhaust elbow and the temps of the exhaust when I'm there later in the weak. If I had to guess, the culprit might be there. I'm getting more steam than what I'd think is normal, and more than comparable camanos, or so it seems.

I did not check the hoses for being "squishy" although I will. I will also disconnect the through hull hose and momentarily open the valve to see that I've got a good flow of water coming up through the valve.

I have not checked the impellers although I don't suspect that is the problem. Water is pretty cool around here and I've just never had a problem with any significant growth as long as the boat is being used. But I'll check anyway since I'm planning on putting the boat on a grid this weekend to change the zincs. I meant to do it a couple weeks ago but got busy.

I'll eventually get it chased down. Just one of those PITA boat things.

thanks again for all the help. and I'll report back

toni

 

[ctjstr]

OK, found the culprit and have a couple suggestions. It was the exhaust elbow. As I hope you see in the photo, the water jacket area is/was toast. New one here tomorrow so back on the water in a day or two.
As for suggestions, first, if you pull the large exhaust hole to check the elbow, be sure to look and feel down in the hose. There was a large ridge of rust cooked on to the hose, such that even with a new elbow, the chances are that quite a bit of the water flow would be restricted by that ridge. Mine was relatively huge, so replacing the hose.

The rest of the hoses were fine.

Also, if you have the elbow out and you pull the small nipple which is where the water goes in, check the seal on that elbow. Its kind of a strange seal, not something you can easily pick up at the local hardware. Make sure you pick one up from the volvo guys or be prepared to make your own.

toni

 

[koliver]

OK, found the culprit and have a couple suggestions. It was the exhaust elbow. As I hope you see in the photo, the water jacket area is/was toast. New one here tomorrow so back on the water in a day or two.
As for suggestions, first, if you pull the large exhaust hole to check the elbow, be sure to look and feel down in the hose. There was a large ridge of rust cooked on to the hose, such that even with a new elbow, the chances are that quite a bit of the water flow would be restricted by that ridge. Mine was relatively huge, so replacing the hose.

The rest of the hoses were fine.

Also, if you have the elbow out and you pull the small nipple which is where the water goes in, check the seal on that elbow. Its kind of a strange seal, not something you can easily pick up at the local hardware. Make sure you pick one up from the volvo guys or be prepared to make your own.

toni

Toni
I am curious to know how old your exhaust elbow is. I have the same TAMD41s, but my Exhaust elbows were installed on the previous TMD40 engines in 1980. When I replaced mine in 2015, they didn't look anything like yours! Nor have I had an overheat issue.
Do you have any idea why you had the rust buildup you show?

 

[Durant F]

The mixing elbows tend to do this if operated at continual low rpm and not “cleared out” every other run with a full or close to full throttle bust for 5-+ minutes.

 

[ctjstr]

Keith
Far as I know, they are original, from 1997. If you look around, you'll discover that this kind of buildup/corrosion is not all that uncommon on these elbows when they get up around 15 years or so. The good news is that it was relatively cheap, as far as volvo goes. Cost me about $275 ordered from Canada...that includes the extra 10 bucks for the trump tariff. I do know that if you don't occasionally run the rpms up for a bit, that you'll build up bunch of carbon,or soot, but I've no idea if that causes corrosion as Durant suggests. I know its a good idea to run the engine up so its at something like 80% of its power, but far as I know that is to help disburse the soot and prevent it from loading on the turbo fins and increasing the liklihood they get unbalanced and contact the housing. I suppose if you build up a bunch of carbon right at the the outlet of the turbo, maybe it can somehow contribute to corrosion, but when you look at how the thing is constructed, where the exhaust comes in, where the water comes in etc, I just don't see the connection. Could be something as simple as higher engine rpms generates more water flow and it helps "wash out" the elbow. Or the higher rpms generate more heat that cooks off the excess soot...Someone smarter than me must know.

toni

 

[kapnd]

The mixing elbows tend to do this if operated at continual low rpm and not “cleared out” every other run with a full or close to full throttle bust for 5-+ minutes.

Are you referring to the rust plugged water passages?
Or might you be referring to the soot on the inside of the elbow?
It’s the cooling jacket that is under discussion here.
A fresh water flush following use goes a long ways towards preventing situations like this.
Shame on Volvo (and Perkins, Yanmar and Lehman) for using cast iron for the exhaust elbow! You know their engineers know better...

 

[porman]

After 9 years and 1800 hours on our Camano I took our exhaust elbow off and had a Volvo tech look at it. He said it looked brand new. This was on a boat that was moored in fresh water and spent a cumulative 3 1/2 to 4 months in salt water every year. That 2 hour run from the Ballard Locks to our slip kept things nice and clean.

 

[Durant F]

I’ve had similar problems with Yanmar...
Soot build up more than rust...

 

[ctjstr]

back when I had strainers with metal covers, Groco maybe? I tapped a hole in the cover so I could attach a ball valve and a female hose end. I'd get back to my slip, attach the hose, and start the water running. Then I'd greadually close the seacock and run the engine on fresh water for a while. No idea how much it may have helped, but it was pretty easy and inexpensive and made me feel better. It was more hose running the hose than anything else.

 

[firehoser75]

Exhaust elbows are "disposable" items. They don't last forever, especially those made from cast iron. If you have a turbo, under the "wrong" conditions, a failing exhaust elbow can send salt water into the turbo (expensive) or worse yet into the engine (really expensive). Freshwater flushing of your system (as often as possible is best) will prolong the life of your saltwater components and allow you to increase the time between major servicing of your saltwater cooling side.
If your aftercooler is saltwater cooled, I would suggest pressure testing it after servicing (reassembly) as any leaks (even very small ones) could be very bad for your engine.

 

[Sweet Dreams]

I hope to figure this out on Thursday when I get a chance to get some stuff done, but any suggestions would be appreciated.

About 3 months ago I started noticing the engine getting a bit warm as I ran it much over 2500 rpm. Not a big deal but something to check on when I had a moment

A short time later, I had reason to go though all 4 coolers on our Volvo tamd41, replacing the oil cooler and thoroughly cleaning the other 3.
ever since, teh heating issue has not gotten better. In fact, its gradually worsening. I replaced the impeller, checked the water intake strainer and checked the two thermostats. No love there.

I'll try and run it down more thursday by checking that the water intake through the hull is clear and trying to spot the hot spots with a temp gun.

Any other thoughts/suggestions?

thanks

toni

Did you have an impeller blow apart? If so the models 40 and 41 are famous for pieces of the impeller getting stuck in hoses and cooling lines to and from the pump.

 

[kchace]

Shame on Volvo (and Perkins, Yanmar and Lehman) for using cast iron for the exhaust elbow! You know their engineers know better...

Later model Lehmans 272x's came with Stainless Steel mixing elbows. Northern Lights also now has (at least for replacement) SS elbows.

Ken

 

[ctjstr]

Did you have an impeller blow apart? If so the models 40 and 41 are famous for pieces of the impeller getting stuck in hoses and cooling lines to and from the pump.

nah...impeller fine. It was that elbow. Took it our for a spin and it ran up right close to 4k. Backed it off and ran for 20 minutes with no heat up. Happy camper now.

toni

 

[ctjstr]

Later model Lehmans 272x's came with Stainless Steel mixing elbows. Northern Lights also now has (at least for replacement) SS elbows.

Ken

Greenwater exhaust has nice stainless parts. I used them on Hino's. I was hoping they had one for my volvo tamd41, but no luck. Found it in BC for half price, so if it only lasts 10 years, I'll buy another.

toni