Corrosion on Volvo 290 "Cowhorns"

[Callisto]

Corrosion on Volvo 290 \"Cowhorns\"

Hi Folks

can anyone offer any advice please. I have a small amount of corrosion at the tops of the exhaust "cowhorns" where they meet the high risers. Basically, the bit under the flexible connection hose has eroded a little. They don't leak and the flexibles cover the area and make a good seal, however, I have the engine out at the moment and want to do everything I can around the engine bay whilst its out. I could take them off and get them welded up before I put the engine back in but a mechanic has mentioned that Volvo did a retrofit kit consisting of an epoxy resin and a plastic sleeve that went over the ends. This apparently was a recognised service procedure, but I cant seem to locate the bits anywhere.

Anyone heard of this or done it and is it any good.

Any help very gratefully received.

Callisto /forums/images/graemlins/smile.gif

 

[Piers]

Re: Corrosion on Volvo 290 \"Cowhorns\"

Yes, I've heard of the insert. It's necessary to prevent non-similar metal corrosion. Before the insert was developed there used to be nothing to stop the corrosion, and I know of one boat that ended up sinking because of it.

I believe you will find it's now a standard service item to check, but it's one of those almost impossible things to do - space etc.

I find it hard to think that Volvo don't know of their own mod!

 

[Callisto]

Re: Corrosion on Volvo 290 \"Cowhorns\"

Thanks for the reply Piers, Much appreciated.

My local dealer was very vague about it initially but when pressed, they did chase down the items and it was odd that they were the same part number for all drives even though they are different diameters?? Nonetheless, they think they can get them and thats good news.

As to doing it, its not a problem at the moment as with the engine out, I have a lovely big hole to work in. So, I have the opportunity to do all those delightful jobs like painting bilges etc that we all enjoy so much.

Thanks again

JH

 

[Col]

Re: Corrosion on Volvo 290 \"Cowhorns\"

Only available for diesels. If yours is a diesel I will look up the pt no: for you.

 

[Callisto]

Re: Corrosion on Volvo 290 \"Cowhorns\"

Hi Col.

Petrol I am afraid. AQ211A with a 290 SP drive.

If only available for diesels, I may be out of luck and have to get it welded up as per my first post. In truth I didn't really want to do that as I don't know if the welding process will weaken anything or what distortion may occur as a result but I may not have any option.

Thanks for your offer of help, very much appreciated.

Regards

JH

 

[Dave_Snelson]

Re: Corrosion on Volvo 290 \"Cowhorns\"

Hi Callisto - Col has a wealth of info here, so i don't want to usurp him here, but if you get stuck, there is a great engineer in the north that you can phone for advise. Its Rob Walker and he is a gold mine!! His number is 07718792509 - and you can tell him I sent you.

Cheers
Dave

 

[Col]

Re: Corrosion on Volvo 290 \"Cowhorns\"

In that case I would get new Tops machined up, lop about 4"-5" off the tops of the old cow horns and weld the new tops on (You have to cut down below corrosion because you can't weld to corrosion)
I can do this for you if you get stuck. Cow horns have to be removed of course.

 

[kds]

Re: Corrosion on Volvo 290 \"Cowhorns\"

Geeee ...
You mobos have got it all tied up - and I thought only Harleys had cowhorns !
Silly old me.

 

[Callisto]

Re: Corrosion on Volvo 290 \"Cowhorns\"

Thanks for all the help folks, I have now got it all sorted out.

I did say at the start that it was very minor erosion around the ends and I have now resolved it by totally grinding out the bits that were pitted down to good sound aluminium and rebuilt it back up to profile with a 2 pack epoxy chemical metal that is suitable for use on aluminium, resistant to sea water and good for continuous operation at 300 degrees C. If the water cooled exhaust ever gets to that temperature I am in really big trouble!!!

Once back into shape, its all been painted up with a high temperature paint (550 degC) to protect everything.

They look like new now and considering the Volvo Penta want about £800 for a new set, I'm quite pleased about that.

Thanks again and if any of you get to Falmouth in the season, there's a beer waiting for you.

JH