Manifold Leak Suggestions Please

[griston64]

Originally Posted by Steve 940

Hi Mark,

Good shout for a possible fabricator, think the wallet is shuddering at the thought 😀😀

Cheers
Steve

He made me a lower chassis brace which was fantastic and very good price wise.

[lynns hubby]

Hopefully, as has been mentioned earlier, it could just be a gasket. This is not unusual on these engines. As Dave says, be mindful with the material choice for studs etc. Aluminium is particular susceptible to electrolytic action from dissimilar metals.
I remember when manifold nuts were made of copper. Never got the problems we get now as it was sacrificial so as long as you used the correct tight fitting tools, all it done if it did not want to come off was strip the thread in the nut. At least that left the stud where it was with out shearing it off in the head which is a right nightmare.

[Steve 940]

Update,

Thought I'd try tracking leak using workshop vacuum with pipe in the vacuum blow outlet, good old gaffer tape for vacuum hose to exhaust tailpipe leaving a small gap.

Hand trigger spray bottle with fairy liquid solution, turned on vacuum, and lo and behold, more bubbles than you'd see at old Upton Park!!😀

Have two sources, Turbo to manifold looked perhaps the worst leak, Turbo to downpipe had a lesser leak, but a leak no less.....

Any suggestions on parts needed to repair this would be most appreciated please, I understand no gaskets as they came out of factory. Looked at the GCP parts list and I think I've attached the screenshot of this, fingers crossed.

1. Turbo oil pipe, looks to need gasket and o ring/seal at lower end?
2. Turbo coolant pipes look to have banjo bolts with two washers at each fixing, can these be re-used or are they like oil filter crush washers??
3. New studs and nuts on both joints?

Anything else, I do have a tube of normal exhaust assembly paste, to use on mating surfaces or not? I would obviously give all mating surfaces a very good clean.

Many thanks,
Steve

[Steve 940]

Many thanks Lynns Husband,

Great points, thank you, I did find on a fastener supplier website some copper and brass nuts along with various sorts of studs.

Looks as though my issue is the two turbo joints, so new studs and nuts there will be needed.

Don't suppose there's any way of finding out the stud specs needed as Volvo studs for manifold to head were a tad pricey??

Cheers
Steve

[Laird Scooby]

Originally Posted by Steve 940

Update,

Thought I'd try tracking leak using workshop vacuum with pipe in the vacuum blow outlet, good old gaffer tape for vacuum hose to exhaust tailpipe leaving a small gap.

Hand trigger spray bottle with fairy liquid solution, turned on vacuum, and lo and behold, more bubbles than you'd see at old Upton Park!!😀

Have two sources, Turbo to manifold looked perhaps the worst leak, Turbo to downpipe had a lesser leak, but a leak no less.....

Any suggestions on parts needed to repair this would be most appreciated please, I understand no gaskets as they came out of factory. Looked at the GCP parts list and I think I've attached the screenshot of this, fingers crossed.

1. Turbo oil pipe, looks to need gasket and o ring/seal at lower end?
2. Turbo coolant pipes look to have banjo bolts with two washers at each fixing, can these be re-used or are they like oil filter crush washers??
3. New studs and nuts on both joints?

Anything else, I do have a tube of normal exhaust assembly paste, to use on mating surfaces or not? I would obviously give all mating surfaces a very good clean.

Many thanks,
Steve

The oil drain pipe from the turbo does seem to be quite common on the O ring where it enters the block - Volvo for that one!
False economy trying to re-use the copper crush washers on the banjo fittings and worth renewing the coolant hoses if you distrub them - they have a tendency to fur up inside and block.

As for the gas leaks, first thing i would try is removing the turbo, cleaning all mating faces and threads then refitting. Don't use exhaust paste as you don't want that getting into your turbo or your cat!

[TonyS9]

My Turbo-manifold leaks slighly, I'd say its fairly normal and should not cause overfueling. You need a big leak, like an actual hole to be blown out of the manifold to confuse the O2 sensor with fresh air.

If you are getting ticking from the exhaust, then you have large cracks or failed manifold-head gasket. Even then I've never found it causes huge fueling problems. The overfueling range oin the O2 sensor is not that much, overfueling is more likely to be caused by temperature sensor problems.

The proper Volvo manifolds can be fairly easily MIG welded, they are good quality, grid out the cracks with a burr and pre-heat in the oven, then after-heat to relax it and control cooling.

A bit of tissue or paper on a stick is a good leak detector.

If you can't inspect it just get on with it and take it off.

[Laird Scooby]

Originally Posted by TonyS9

The overfueling range oin the O2 sensor is not that much, overfueling is more likely to be caused by temperature sensor problems.

The ECU is programmed to increasingly and continuously over-fuel until it sees a result from the Lambda sensor at which point it changes to lean again and conitinues the lean/rich cycle to maintain what it percieves as the correct mixture.
As such you can get some serious overfueling from a dead lambda or indeed from one that is "confused" with extra air leaking into the exhaust.

[Steve 940]

Thanks Dave and TonyS9'

Thanks very much for information, think I'll leave this then till I have a period when I can afford to have it off the road for a couple of days to sort it properly.

Nice to hear that small leaks shouldn't cause overfuelling issues, perhaps my mpg drop has been caused more by my right foot😀

Tried getting soapy water on manifold to head, rather difficult to get at, but couldn't see any leaks using a mirror and light to try to look underneath it.

Will try to pull together all the bits I'm likely to need, probably will also need new joint from front pipe to cat As the pipe looked good but joint was a bit crusty.

Nice little Xmas project, although not sure better half would agree!!

Cheers
Steve

[Laird Scooby]

There are a few reasons your mpg has dropped Steve, all come back to the leaks though.
First is obvious lack of back pressure. Rough rule of thumb is the closer to the manifold the leak is, the bigger the drop in economy.

Second is the turbo isn't getting the full benefit of the expanding hot exhaust gases to spin it up. As such, you're using more throttle to get moving, more throttle = more fuel in but because of the turbo losses from the leaks, only the same result in speed.

Third, as already mentioned, the Lambda sensor will be slightly confused so the ECU will be adding more fuel to compensate.

A thought crossed my mind if you find the mating surfaces of the manifold and downpipe and turbo flanges are pitted with rust that can't be sanded out easily. You could make gaskets from copper shim sheet. I'd suggest ~1mm thick and you could use the same method as for making gaskets using cardboard, rubber, cork etc by laying the sheet on the item to be gasketed and using the ball end of a ball-pein hammer to tap round the holes. I would suggest annealing afterwards, heat the gasket evenly with a blowlamp until it's just about cherry red, you can either quench in water or allow to cool naturally (softer result which would probably be better for a gasket) then fit the gasket and tighten it. Also once the engine is hot, CAREFULLY (you don't want burned paws! ) slacken each fastening 1/4-1/2 turn then retighten to the specified torque.

This hot retorquing will also work if you don't make gaskets and is useful for all exhaust connections.

[Steve 940]

Hi Dave,

Once again thanks so much for 'top tips' on this, and as you may have guessed it's a bit of astep into the unknown for me, not having done this before.

Yes I do want a belt n braces backup, as often things don't go to plan.

Copper shim sheet? Sorry to be a numpty, do you mean 1mm thick copper sheet, or is it a gasket material sandwiched between copper sheet. I have some old normal gasket paper for making up one off gaskets, but obviously not suitable for exhaust use.

Stud extractor, any suggestions on 'best' sort please, seen some that look to work with a serrated cam onto socket drive, something like this??

https://www.ebay.co.uk/itm/262046137...yABEgL3gPD_BwE

Would you pull manifold and replace head to manifold gaskets at the same time, or leave alone?? Obviously if I get Turbo off, I will check manifold carefully for signs of any cracks, white / grey deposits. Just don't really want to risk shearing a head stud if manifold itself is not cracked.

Cheers
Steve