Exhaust Elbow Removal - Stuck Nuts (Volvo MD2020D)

[steveej]

Good morning,

I have been having engine overheat issues all season on a new to me boat with Volvo MD 2020 D engine.

Heat exchanger is all clean and has been flushed but it appears that the exhaust elbow is blocked and so I need to take it off. The top two nuts I have managed to release but the bottom two are absolutely solid. Access is also severely, sockets will not fit and the only thing I can get on them is a stubby ring spanner. After two weekends of trying the nuts are still ok but they are starting to deteriorate.

I cannot run the engine up to heat it up as coollant has been drained and the exhaust is blocked in any case.

Someone recommended using a 'crème brulee blow torch' to burn the paint off the nut and then spray with penetrating oil which I plan to do this weekend but I am concerned about damaging some of the electrical wiring close by.

Does anyone have any more tips of things I could try? I have heard of freeze spray but have never used it. Any issues with heating up the elbow and then spraying the nut/stud?

 

[john_morris_uk]

Good morning,

I have been having engine overheat issues all season on a new to me boat with Volvo MD 2020 D engine.

Heat exchanger is all clean and has been flushed but it appears that the exhaust elbow is blocked and so I need to take it off. The top two nuts I have managed to release but the bottom two are absolutely solid. Access is also severely, sockets will not fit and the only thing I can get on them is a stubby ring spanner. After two weekends of trying the nuts are still ok but they are starting to deteriorate.

I cannot run the engine up to heat it up as coollant has been drained and the exhaust is blocked in any case.

Someone recommended using a 'crème brulee blow torch' to burn the paint off the nut and then spray with penetrating oil which I plan to do this weekend but I am concerned about damaging some of the electrical wiring close by.

Does anyone have any more tips of things I could try? I have heard of freeze spray but have never used it. Any issues with heating up the elbow and then spraying the nut/stud?

I can't think of any wiring nearby that couldn't be moved away from the blowtorch. I agree that access to those nuts is challenging, but I think by now I'd have resorted to drilling through the side of the nut and using a small metal chisel to get the thing off!

I hope that you manage to decode your exhaust elbow satisfactorily. I tried a whole mixture of chemicals to deck mine a few years ago, but I discovered that the best one for the carbon build up was oven cleaner...

 

[RichardS]

Would it be possible to use a 1/4 inch drive and a short socket with a combination of wobble bar extensions and a universal joint? There is a nut on one of my cars which has a very cramped engine compartment that is impossible to get at any other way, and even then it's a matter of feeling my way in as the nut is virtually impossible to see.

Richard

 

[Yellow Ballad]

If you can get in I think I would be using a dremel cutting disc and cut the nut off, or as above cut/drill and a chisel as this will probably be what you'll end up doing.

No harm in trying a 6 point spanner first though rather than a 12 point one.

 

[Poignard]

Can you get a crowfoot spanner in there?

https://www.bahco.com/en/s/crowfoot-wrenches/52-24-e4-30-a0-ec-aa-c8-cc-b3-ff-56-b8-54-a8-d5/


A tip for when you fit the new one:

Use brass nuts and they will never seize.

 

[Neeves]

I cut the side of the nut off, carefully, with an angle grinder (though it might have been a bit of a hacksaw blade with a little handle) and the nuts then came off, easily. You need to be careful not to cut the thread of the stud. Its still not easy - the man who designed it all needed to have his head examined. Wait till you take the water pump apart when the seals fail (nuts, bolts or studs - equally inaccessible - I cut up spanners to 30mm long simply to get access.

Take the rubber hose of before you take the elbow off. Its easier (as the elbow is still fixed).

I've cleaned ours once, the second time the acid, HCl, put a hole in the elbow. Its primarily calcium carbonate with a lot of carbon. I then had to buy a new elbow.

Good luck

Jonathan

 

[steveej]

Not enough access for crow foot wrench or grinder.

1/4 inch, 12mm socket I can get on the nut but due to the curvature of the elbow, the female drive of the socket is concealed meaning I can't get a handle on it.

The stubby 12mm ring spanner fits but because it is so seized the nut is starting to warp.

I think I will try some heat otherwise it will have to be cut off and I'm worried about messing up the stud.

 

[john_morris_uk]

Not enough access for crow foot wrench or grinder.

1/4 inch, 12mm socket I can get on the nut but due to the curvature of the elbow, the female drive of the socket is concealed meaning I can't get a handle on it.

The stubby 12mm ring spanner fits but because it is so seized the nut is starting to warp.

I think I will try some heat otherwise it will have to be cut off and I'm worried about messing up the stud.

I wouldn't lose too much sleep over messing up the stud. There's nothing special about it and when its not under tension, and with access much improved, I expect you'll get the stud out fairly easily and replace it with a new one. The only thing special about it is if you buy a Volvo one in which case it will be especially expensive.

 

[vyv_cox]

When I used to do a lot of semi-professional work on old bangers I never found a nut that would not come off after heating to red hot.

 

[steveej]

Thanks everyone.

Anyone know how difficult is it to remove the entire heat exchanger housing? This may need to happen anyway because if the blocked exhaust does not solve the over heat issue, my next line of enquiery is the thermostat for which the housing needs to be removed.

I'm thinking lets remove the whole lot, replace thermostat for piece of mind and easier to get the elbow off.

 

[RichardS]

When I used to do a lot of semi-professional work on old bangers I never found a nut that would not come off after heating to red hot.

Although I doubt whether a creme brulee torch will deliver that much heat, unfortunately.

Richard

 

[VicS]

Blueberry Crème Brûlée ......... good

Recipe:- https://www.aldi.co.uk/blueberry-crème-brûlée/p/000000007538900

 

[peteK]

I have the same exhaust elbow it usually gets partially blocked in the half inch spigot that the rubber boot fits over which restricts the water flow,ream it out with a drill bit.

 

[brians]

Removal/replacement of the heat exchanger is a simple DIY job. I did it a year or so back but had to replace the exchanger for which VP charged £1000+.

 

[scottie]

Could you get a nut splitter tool in?
https://stuccu.co.uk/afr2?d=ST___Fb...32v9q/cmjZGaUgaUFyRC9JNDr+OnMH4IEgRtNfV8ED___

 

[yimkin]

I have had success applying heat to siezed nuts using a large electric soldering iron followed by plusgas. If the iron can be propped in contact with the nut to allow a heat soak all the better. Its not as efficient as a flame but its easier to handle and works ........eventually.
I have an old Volvo MD2010 shoehorned into a small double-ender and I too have wondered about some design detail decisions on Volvo engines but suspect they were designed for use on plant with all round access rather than boats.

 

[Neeves]

Basically they are, or were, a Perkins engine, made in Japan and in our case bought off the shelf and modified by Volvo, using more parts they bought in, to convert for marine application. I think the Perkins design was probably very clever as it allowed the basic engine to be used in a whole range of different applications - sadly for convenience (or poor planning on behalf of Volvo) they are not really user friend for some very simple and basic maintenance tasks. They are enduring - and accept repeated abuse and lack of attention.

I have wondered why the exhaust elbow blocks. Comments suggest that stainless elbow are less prone - though whether this is actually true I don't know - comments?? There are more comments on Volvo elbows than other engines, or that is what I detect - which suggests its a design or configuration issue. It will also be a function of the amount of dissolved calcium in the seawater.

Sorry - this is of no value to the OP - unless he needs to replace the elbow - in which case (if he is keeping the boat) a stainless one might be a better investment.

Jonathan

 

[ghostlymoron]

Johnathan, Yanmars, especially the 10GM, is notorious for coking up and corrosion. The replacements are also eye wateringly expensive.

Basically they are, or were, a Perkins engine, made in Japan and in our case bought off the shelf and modified by Volvo, using more parts they bought in, to convert for marine application. I think the Perkins design was probably very clever as it allowed the basic engine to be used in a whole range of different applications - sadly for convenience (or poor planning on behalf of Volvo) they are not really user friend for some very simple and basic maintenance tasks. They are enduring - and accept repeated abuse and lack of attention.

I have wondered why the exhaust elbow blocks. Comments suggest that stainless elbow are less prone - though whether this is actually true I don't know - comments?? There are more comments on Volvo elbows than other engines, or that is what I detect - which suggests its a design or configuration issue. It will also be a function of the amount of dissolved calcium in the seawater.

Sorry - this is of no value to the OP - unless he needs to replace the elbow - in which case (if he is keeping the boat) a stainless one might be a better investment.

Jonathan

 

[Monique]

I've had all these issues over time on my TDM22 (Volvo). some of the problems with them is Volvo changed some components just for the sake of change... oil filters as an example.

I remove the entire intercooler/housing every 2 years, then at my leisure. Much easier task and i get a good look at all the offending components. GL

 

[scottie]

Basically they are, or were, a Perkins engine, made in Japan and in our case bought off the shelf and modified by Volvo, using more parts they bought in, to convert for marine application. I think the Perkins design was probably very clever as it allowed the basic engine to be used in a whole range of different applications - sadly for convenience (or poor planning on behalf of Volvo) they are not really user friend for some very simple and basic maintenance tasks. They are enduring - and accept repeated abuse and lack of attention.

I have wondered why the exhaust elbow blocks. Comments suggest that stainless elbow are less prone - though whether this is actually true I don't know - comments?? There are more comments on Volvo elbows than other engines, or that is what I detect - which suggests its a design or configuration issue. It will also be a function of the amount of dissolved calcium in the seawater.

Sorry - this is of no value to the OP - unless he needs to replace the elbow - in which case (if he is keeping the boat) a stainless one might be a better investment.

Jonathan

I believe that you will find that the exhaust elbow which is used on a range of HP from 9-100 and the rest of the cooling system is of Perkins origin and that exhaust blocking was not a great problem (but not unknown) before the adoption of Perkins based engines however Volvo,s own elbow dating back to The 60,s did suffer from corrosion eventually
As an observation the VP elbow has a much longer sweep with the mixing point further away from the manifold
The Perkins style along with the Yanmar elbow allowed a better exhaust run which suited flat bottom boats