Engine rebuild project

[stribo]

Looked and sounded good yesterday Rob.

[960kg]

The valve guides where ok with no wear. The head has always been playing on my mind as it could have been a N/A head that has had turbo valves/guides fitted or it`s cracked/porous.

If the bores/pistons are OK then I`m going to get the original head refurbed.

As you know Rob i always get moaned about for my help or thoughts!.........but sitting from where i am reading your project and what you have done and are still doing those oil seals and gaskets were ok as are the stem seals and guides the problem is Old Pistons in Old Bores..... it does NOT work!!!!........you may have had the T4 pistons fitted to a rebored bore but it will NOT work!

I have built so many engines i can`t remember them all but the only ones that were 100% ok were new rebored blocks with new pistons and that was only for producing 120bhp in the early `70`s!

As you know pistons are not parallel they are tapered a worn piston even more so where do you start the measuring for it to fit !!........some say 10mm down some say at the bottom of the stroke for measuring the block to piston clearance.

There are different grades of piston and bores when new in the factory for fit which only differ by a few thou so how can a used 2nd hand used piston give performance bhp with no problems .......it simply can`t......

The reason your oils seals have failed is because you have too much blowpast which gave you too much pressure in the sump even tho you have modified the PCV.

It is not normal for ALL the seals to go is it especially pucker Volvo?

I don`t know if you have figures but bore is 83.015 and piston should be 82.995 with a running clearance of 0.20mm ( 7 to 8 thou)

Minimum is 4 thou and the max is 11 thou running clearance.

Also did you know that the 1st compression ring is larger than the 2nd compression ring.......did you fit them the wrong way around??

Good Luck

Keith

.................................................. ......................

[t5 pete]

sorry but I must dissagree with you your first paragraph is wrong I know this may suprise you but I actually agree with you just goes to show these old ones still have it

[oblark]

As you know Rob i always get moaned about for my help or thoughts!.........but sitting from where i am reading your project and what you have done and are still doing those oil seals and gaskets were ok as are the stem seals and guides the problem is Old Pistons in Old Bores..... it does NOT work!!!!........you may have had the T4 pistons fitted to a rebored bore but it will NOT work!

I have built so many engines i can`t remember them all but the only ones that were 100% ok were new rebored blocks with new pistons and that was only for producing 120bhp in the early `70`s!

As you know pistons are not parallel they are tapered a worn piston even more so where do you start the measuring for it to fit !!........some say 10mm down some say at the bottom of the stroke for measuring the block to piston clearance.

There are different grades of piston and bores when new in the factory for fit which only differ by a few thou so how can a used 2nd hand used piston give performance bhp with no problems .......it simply can`t......

The reason your oils seals have failed is because you have too much blowpast which gave you too much pressure in the sump even tho you have modified the PCV.

It is not normal for ALL the seals to go is it especially pucker Volvo?

I don`t know if you have figures but bore is 83.015 and piston should be 82.995 with a running clearance of 0.20mm ( 7 to 8 thou)

Minimum is 4 thou and the max is 11 thou running clearance.

Also did you know that the 1st compression ring is larger than the 2nd compression ring.......did you fit them the wrong way around??

Good Luck

Keith

.................................................. ......................

If you look you can make out a puddle of oil on top of the valve heads and where it has come out of the inlet ports.

When I was younger a mate of mine rebuilt his 2 stroke motorbike engine and forgot to refit the rings, it smoked abit but it ran.

[960kg]

If you look you can make out a puddle of oil on top of the valve heads and where it has come out of the inlet ports.

When I was younger a mate of mine rebuilt his 2 stroke motorbike engine and forgot to refit the rings, it smoked abit but it ran.

I understand the 2 stroke bit as that is where i started my tuning engines ,i had the Lambretta GT 200 in 1964 ....it had the hemi head design just like Aston Martin and Jaguar so that is where it all started with me and engines.....the 2 stroke will smoke because of the oil mix in the fuel as it doesn`t have a sump for oil!

Not arguing at all Rob as i know you know your engines etc. but why is there oil on the manifold flange gasket?.......as if it`s on the valve head that is where it should only be!....is the oil coming from the turbo?

You say the comp.test was more when you poured oil in the combustion chamber but surely it would read high if the oil was already there via the valves?

Just remembered when doing my first valve lapping in........i didn`t properly wash away all the grinding paste from the guides and after a few weeks of running the engine did smoke badly as the valve guides had worn out of this world!!

There is a problem ,only hope you find the correct answer without stripping all the time!

[oblark]

The oil was only in the valve ports, the throttle and induction pipes are oil free.

I would have expected the compression reading to come up when oil was added to the bores, the higher the reading with oil over a dry test would indicate the rings are not sealing but as it only increased by 4 bar.

before the engine was removed both the pipes that go to the catch tank where vented to atmosphere and even doing that didn't stop the engine from blowing blue smoke out of the exhaust.

My money is on the head being knackered but I could wrong and have been in the past

[FIREBOLT]

Did you wire brush the pistons to clean them?

[oblark]

No, they we're cleaned with degreaser then put in dishwasher.

[oblark]

Pulled the head off the smoking engine today and for a engine that has only done 300ish miles f**k me what a state.

A little puddle of oil in the pistons.



The head looked like it had done 300k miles.



I`ve pulled a inlet and exhaust valve out of the head and the same out of a spare head I`ve got and measured the valve stem dia, A turbo exhaust valve should be 6.960mm and both of mine are 6.959mm. A n/a exhaust valve is 6.70mm so the head with the n/a ports is a n/a head that has the valve guides machined out to take turbo valves as I`ve not found any imformation to say that ports on the head I used was a turbo head, this was one of the things that was on my mind when building the engine. The valve stem seals where not the greatest of seals on the valve mite look into seeing if I can some tighter fitting ones.

Also the valve springs where a different shape, the tapered ones came from a turbo head,



As the spare turbo head I`ve got has 6 bent exhaust valves I`ll be changing over all 20 valves from one head to another (waiting for the "you can`t do that ......")

[960kg]

As the spare turbo head I`ve got has 6 bent exhaust valves I`ll be changing over all 20 valves from one head to another (waiting for the "you can`t do that ......")

You can do whatever you want to do........but you know yourself deep down "you shouldn`t do it"..........if you want a first class engine that is!

All the time and effort and money you have spent on the engine it is only as good as it`s weakest link!

[partsforvolvos.com]

keep at it rob.
this is an interesting thread, loads of threads on bodywork mods but not that many have good detail on engine rebuilds.

[M-R-P]

Nice to see the Haynes book of lies being put to the use it was designed for - protecting a good table

[oblark]

keep at it rob.
this is an interesting thread, loads of threads on bodywork mods but not that many have good detail on engine rebuilds.

Thanks, I`ll be after some bits & bobs in the next few months

[oblark]

Nice to see the Haynes book of lies being put to the use it was designed for - protecting a good table

It was the only flat thing I could find as the valves kept falling over when sttod on the wheelie bin

[partsforvolvos.com]

well they stopped doing the Haynes manual plastic protector wallet so the book had to be used .
we christened it the jizz cover ........ pmsl

[stribo]

Surely if you lap the valves in, then there shouldn't be a problem changing them over.

[oblark]

Surely if you lap the valves in, then there shouldn't be a problem changing them over.

The words nail and hammer spring to mind

As long as the valve guides aren`t worn to badly then it`s just a case of swapping valves over & lapping them in.

[partsforvolvos.com]

changing valve guides is a pita, you have to heat the head to 180'c to expand it.

[stribo]

The words nail and hammer spring to mind

As long as the valve guides aren`t worn to badly then it`s just a case of swapping valves over & lapping them in.

If the valve guides are worn, you'll have a problem whatever valves you put in.

[partsforvolvos.com]

Volvo don't sell guides, but I managed to get some in the past ok.