Rebuilt 1.6 engine, problems advice required.

[skyboarder1001]

Hello all,

Just looking for some advice from some experienced engine mechanics.

I purchased a nova GSi a while back, which had a full engine rebuild prior to me purchasing. I was running the engine in and it was running poor and misfiring and getting excessive oil vapour from the oil catch can.

I did a compression test, which identified one cylinder at 0psi, one at 80psi and I believe the other two were around 175psi. I handed the car to my local mechanic who confirmed the compression test and sent the head away to a machine shop.

The machine shop identified two stem seals not seated / fitted correctly and reground valves, skimmed the head and handed me it back. The head was refitted by the garage and I was told to put around 1000 miles on the car and return to get the head bolts re-torqued. They also told me I would continue to get a lot of oil vapour from the catch can until the carbon builds up around the valves. I've put on around 700 miles and still getting excessive oil vapour from the catch can. When the cars at tickover the oil vapour is coming out the catch can filter like vapour out the exhaust pipe.

The garage recommended putting miles on the engine to build the carbon up in the head. However, reading in other forums some people state this builds up can take 4-5000 miles not 1000. I thought in the meantime I would do a dry and a wet compression test myself to see how things were looking, which unfortunately doesn't look too healthy. Results are as follows;

Cold & Dry Test Cold & Wet (5mm of oil) Improvement
1 - 180psi 1 - 215psi + 17% improvement
2 - 127psi 2 - 167psi + 27% improvement
3 - 135psi 3 - 163psi + 19% improvement
4 - 45psi 4 - 73psi + 47% improvement

So should I continue to put more miles on the engine in the hope compression and blow by improves (I don't see how it would?) or should I be looking further down with the possibility of the rings not sealing or need the cylinders rehoned? If it is the rings can this be replaced with the engine in situ or will it require to have the engine removed and fully rebuilt? Is their any other test that I can do to help identify the root cause?

Any help or advice appreciated, thanks

[Evoluzione]

You've been ripped off, you need legal advice, not engine advice.

[paintman]

If there's now nothing wrong with the head it sounds very much like problems lower down allowing excessive blowby on at least one piston causing excess pressure in the crankcase which has to go somewhere so it's out of the breather.

Don't bother about this 'waiting for carbon to build up' business.

Think you were sold a pup from the outset.

Edited by paintman on Thursday 8th July 01:20

[Rich1973]

If you are happy that the head work has been done correctly then as said above, your issue now lies in the block.

[Mave]

Presume the cylinder with low pressure now is the one which had zero before? Looks like it's improved a bit with the head work, but theres still a bore / piston ring problem. What did the garage say about the bore condition when they had the head off?

[Zener]

If its crankcase breathing its piston/bore or ring related or all three , like suggested find someone that knows what they are talking about than that machine shop "carbon crap" advice you was given

[paintman]

Makes me wonder what was actually done during this supposed 'rebuild' before you bought it.
Perhaps one of the 'give the outside of the engine a good clean and perhaps a bit of paint & polish' variety.

Valve stem seals are intended to prevent oil leaking down the valve stem.

The valve stem should be a good fit in the valve guide.
If either are worn you are likely to find blue smoke from the exhaust especially on startup after standing due to oil leaking down the stem & either being drawn into the cylinder & burnt if it's the inlet valves or being burnt off if it's the exhaust valves & perhaps a little extra breathing.

Properly fitted valves should seal on their seats without anything else being required.
If an engine required a build up of carbon for valves to seal properly then you can just imagine the fun & games with brand new cars!
Plus carbon buildup primarily appears on the exhaust valves not the inlet valves as it's a product of combustion.
I'm talking here about the stem side of the valves, not the parts that face into the bores.

I think you need the engine stripped & properly examined - if only to check that each piston is the right size, has the right number of rings fitted the right way & they're intact!
Bores need to be measured for wear & any ovality or other damage. Just randomly honing the bores without checking is pointless.

Edited by paintman on Thursday 8th July 11:24

[stevieturbo]

As others say, what a load of bks.

0 compression would tend to be no valve seal ( in terms of sealing, not an actual stem seal )......stem seals would do feck all apart from perhaps cause smoking.

So this head rebuild perhaps seems questionable, and are such engines not prone to the hydraulic lifters pumping up after a rebuild and holding valves open ?

Really though, sounds like you've been hit twice here. By the original seller and the incompetent garage in the second.

The fact they would try and spin some BS about it taking 1000 or more miles to ome good, or indeed the head needing re-torqued, is just utter nonsense

[skyboarder1001]

Thanks for the comments folks. To try and answer some of the points raised above.

I purchased the car years back when they were weren't selling for silly money. It had a full photo documented nut and bolt restoration done by the previous owner all new GM parts. The previous owner was a genuine enthusiast who spent years restoring the car. I cant really complain too much as I picked it up for a great price for what their selling for now......... However, your right engine wise it's “a pup” as obviously it would have been a significantly much better buy if the bloody rebuilt engine was actually done correctly and worked properly.

As a few of you have said it’s going to need a strip down and proper examination. It does sound like a bottom end issue and going to take the car elsewhere to get looked at as the current garage isn’t anywhere spending enough time to diagnose where the problem lies and I’m just getting the run around with them. Very frustrating as I’ve used the garage for many years and know the owner (who’s don't the work) well!

I’ve reached out to a few places I’ve found via Google to quote me for a rough idea of a rebuild. The ones that have got back to me thus far haven’t filled me with confidence. One came back quoting a 6 month lead time which I was thought was ridicules as it's a fairly basic Vaxhall engine. Another offered to strip it down to ascertain the problem for free, but no indication of potential best or worst case costs which I guess would them be stuck using them to charge whatever they want with a block lying in bits?

I’m currently looking though forums and reaching out to other garages / mechanics I've used in the past to try and find a reputable engine builder with good reviews and recommended by someone I know.

The whole sage is turning into a right royal pain in the ar$e but ho hum just gotta keep at it. If anyone can recommend one please drop me a message. I’m located in Scotland if that helps?

[stevieturbo]

With it being such a simple engine, it's, a shock any garage couldnt diagnose it ( well...not really )

Long lead times at some garages may not be unusual, often many do not do engine rebuilds, and parts and machinging lead times can be long, so stuff like that ends up pushed to the side.

I'd say you'd be best reaching outon some Vauxhall forums to ask for anyone local to you whop is at least half competent to look at it and diagnose any issues. Scotland is a big place too, so be a little more specific.

Although again as an old car, even a Haynes manual might be some use to you.

Jumping to conclusions that the engine needs totally rebuilt is a little extreme without a proper diagnosis.