Head Rebuild?

[Guest ASH83W]

Hi all! Would like your opinions please?

 

I have done a compression test on my 1.6 Gti. All four cylinders were 150 Psi. The fact that all four are the same is good but 150 psi is a bit low isn't it?

 

Would you recommend having the valve seals replaced with the head on or recommend having the head taken off and rebuilt? Its done 120k.

 

Also whats costs would be involved and can you recommend anyone in the worcesterhire/warwickshire area? I would attempt the work myself but I live in an apartment and the garage I rent for the pug is tiny and has no lights/electrcity!

 

Cheers people!

[Guest ASH83W]

Forgot to mention it burns oil and puffs a small amount of blue on tick over.

[Miles 331 1 Cars]

If compession is low I;d get a leak down test done as this will show where the problem is, but it sounds like a rebuild is needed, Or have a look on the bay as there are a couple on there at the moment

[Guest ASH83W]

How do I do a leak down test? Am I right in thinking the valve stem seals would be the problem, and can they be replaced with the head in place. Or should I just bite the bullet and have the head rebuilt?

[boombang 2]

Valve stem seals won't have any effect on cylinder compression! They sit on the valve stem top and stop too much oil passing down valve stem - which is above the valve guide and nowhere near the valve face.

 

If the engines old and had enough use that stem seals are knackered, then chances are head gasket and possibly valve seats could do with freshen up, along with head face itself.

 

Don't mess about changing in situe, is fiddly and IMHO a false economy when you'd benefit from having a fresher head on there.

 

Leak down test is basically pressuring each cylinder with valves shut to see if and where compression is being lost from.

Edited November 22, 2009 by boombang

[Guest ASH83W]

I have carried out another compression test after pouring a drop of oil into each cylinder. Each cylinder was higher 180-200 psi. Does this point to stem seals?

 

Just trying to determine whether the low compression is due to a head problem or bottom end? The engine sounds fine and pulls well.

 

Many Thanks.

[Guest ASH83W]

No Mayo in the oil and coolant level stays the same.

[James_R 3]

IF a dash of oil has bumped thing that much up with either rings, or you put lots of oil in (take up unswept space and can give a faulse reading)

 

But if not too much oil was used the rings sound like they need replacing. The stem seals would show up as a puff of blue smoke on start up and overrun when the car's warm

[Bottrill 0]

I had the HG go on my 1990 1.6 GTI two weeks ago after only a week of ownership. After the removal of the head, the HG was a complete mess, corroded pretty much everywhere. I decided to completely re-build and clean the head. The valve stem oil seals were rock hard and weeping in cylinder one. At the end of the day the car is 19 years old.

 

My advice would be to take the head off, give it a good clean, and refit with a complete new gasket set and valve stem oil seals, even get the injectors serviced if you can afford it.

Edited November 30, 2009 by Bottrill

[ALEX 98 1 Cars]

Did you do the test with the throttle open?

[Guest ASH83W]

Thanks for your replies everyone!

 

Yeah throttle fully open. Wouldn't the fact that the compression increased with the drop of oil point to piston rings tho? There is no point me rebuilding the head to find that its the same once built back up due to the rings?

 

I have sourced a low mileage 1.6 unit so was just going to plonk that in I think.

 

Cheers!

[ALEX 98 1 Cars]

It is looking like the rings are a bit worn then. Is it burning much oil when warm, (does the exhaust stink of old engines, or is it giving off blue smoke)

If you do fit another engine, don't throw away / sell your old one just yet.

I've bought a low mileage engine before, ended up worse than the one I was replacing.

Edited December 1, 2009 by ALEX

[Guest ASH83W]

Yeah I was gonns keep the old unit as a spare just in case. Its not burning loads of oil. The exhaust does smell strong and when revved hard does puff a bit of blue but not clouds! It also puffs a bit of blue on tick over. I have been struggleing to get the co2 below 3-4 also. I think its just a bit tired.