Volvo Penta TMD31A Replacing exhaust elbow

[george123]

I have just removed the exhaust elbow on my Volvo Penta TMD31A engine. I will be ordering new v clamp, gaskets, and hose. The question that I have when I replace the gasket that goes between the elbow and the turbo (this is where the V clamp is used) do I leave the gasket dry or do I use some gasket cement to help seal the two surfaces? Also the gasket that goes between the water supply flange and the elbow do I use cement as well? When I rebuilt auto engines many years ago I would always us gasket cement.

I am also looking for a supplier in the US that I can get the parts at a reasonable price. I contacted a Volvo dealer and there prices are very high.

Thanks

[DougR]

There is no gasket between the turbo flange and the exhaust elbow flange....metal to metal contact held together by the band clamp.

Depending on the elbow, there will either be a rubber seal or a paper/fiber gasket on the water connection to the elbow. You can use a gasket cement, but it's not really necessary.

DougR

[Lepke]

Try here:
Marine Engine Service - Marine Exhaust Manifolds, Volvo V6, V8 307 - 350 cu.in.
For stainless try here:

https://greenwatermarine.com/product...l-engines.html
Also try ebay. There are new and used usually for sale.

[george123]

If you look at the engine parts break down there is a gasket between the elbow and the turbo. It is item #25 Gasket #859052.


I was thing of using Permatex auto gasket paste.

[jimbunyard]

The #25 gasket is superfluous, I have a TAMD41, no gasket is necessary. Some kind of gasket dressing between the turbo and manifold shouldn't be needed if the surfaces are good, but as you're sealing water and exhaust gases at that joint, it won't hurt anything, and may be beneficial to use it there.


As Volvo makes this engine themselves, beyond things like the starter, alternator and raw water pump (Johnson) and possibly some internal turbo parts and exhaust els, most internals have to come from them. However, as the engine is pretty old,
there may some internal parts like engine bearings and gaskets that are available, especially if you try European sources...

[Squanderbucks]

Have a look at high copper sealant by permeated. I was told by my turbo supplier to use it on the turbo/manifold gasket and at the turbo/riser connection.

[DougR]

Originally Posted by george123

If you look at the engine parts break down there is a gasket between the elbow and the turbo. It is item #25 Gasket #859052.


I was thing of using Permatex auto gasket paste.

A little (ancient) history....
When the Volvo Penta 30 and 40 series were introduced in the late '70s, the exhaust mixing elbows for the turbocharged and turbo/aftercooled engines were made of all cast iron and clamped to the turbo outlet flange with the band clamp that you refer to. Because these elbows mixed the seawater with the exhaust gases, the water passages were always subject to rusting and eventually closing off and restricting water flow. Some years later the elbow was redesigned and it was changed to an outer cast iron "shell" with an internal stainless sleeve. This reduced the amount of rusting by 50% and also allowed the water outlets to be made larger and last much longer before getting restricted.

When this new style elbow was assembled at the factory, a gasket was used between the flange on the stainless insert and the cast iron shell to prevent water from leaking into the exhaust stream and possibly back into the turbo. I think this is the gasket which you see shown on some of the parts breakdowns.
You'll notice it's only shown on a few of the breakdowns.....

If you use this fiber gasket between the two flanges two things might happen:
- it will move the flanges far enough apart that the band clamp will probably no longer be able to grab and hold the elbow....because the band clamp is a tight fit on the flanges
- even if you get it installed, over time the fiber gasket will burn thru from the exhaust gas temp. and an exhaust leak will occur.

As Jim states, the gasket is not necessary..

DougR

[george123]

This is a very interesting response. The old elbow does have the SS insert that you mention. When I remove the old elbow there was a gasket around the SS. I was able to clean that away. When I looked at the turbo mating face you could see that the turbo was machined to except the gasket so that the two surfaces would mate. My concern is that the turbo face is not a polished machine surface and the gasket would be needed to make sure there is a positive seal. I will be using a high temp gasket paste just to make sure that things will seal.

Thanks

[DougR]

Interesting that your turbo has a recess machined in the flange to accept a gasket...

Without exception all of the 30,40, 41,42 43 and 44 series engines I have installed had no gasket on the turbo flange. However, if your turbo flange has a recess for the gasket, and the recess will allow the band clamp to pull the two metal flanges together, then it should be OK to use the gasket.

DougR

[george123]

Thanks Doug

We will be reassembling next week if the parts come in from Marine Parts Express.

George

[Ahab2]

Dear members of this forum,

This is my first post because normally I have always found the answer to my questions reading the old posts. Also it's difficult for me helping anyone because the only thing I know about sailing, cruising, my boat is that I know nothing.

Finally, apologies if I refloat this old post but my question is pretty much related to this thread so it can be useful for someone that search the web looking for solutions to problems with exhaust elbows.

Now the question. I have a Volvo D2-55 which I think it's the same engine than the D2-75 but without the turbo. The engine has 20 years but 1.000h and previous owner never had a look to the exhaust elbow, so I decided to check for inspection and I found that, as expected, the elbow is the original and not much carbon deposits or rust was clogging it. I cleaned with acid and put it back with a paper gasket that I bought.

The problem is that I saw that in the middle of the bottom part of the heat exchanger, were it joints the exhaust elbow, it was a little bit distorted. I tightened the nuts as much as possible but I feel the gas coming out. Anyone has experience the same or can tell me how can I fix the problem?

Thanks all in advance!