engine problem, is it caused by the gas system?

[jalfrezigazee]

My car is an Astra VXR running a Prins setup with approx 295bhp. It has the turbo kit fitted with brown injectors

At 60k I had new brown injectors fitted as firstly one then a second of the original ones used to stick open causing a misfire. At first Prins were not going to change the injectors under warranty so I bought a single injector that I lucky found then when the second failed I got the warranty claim sorted

Soon after this I got a misfire on the car for a few seconds when starting it up which no-one could find the cause. It went to Vauxhall, a specialist Vauxhall race car place and the LPG people to be looked at many times. Eventually the misfore got so bad that I decided to do some diagniostics myself. I did a dry compression test from cold and found that cylinders 1 and 4 were very low. So I put the plugs back in fired it up and after about 30 seconds the misfire cleared so i did the compression test again and all cylinders were 10 bar. A few days later the cylinder head sopunded like there was a grinder inside I got the car send to the VX specialists

They stripped the complete engine down and found no fault so blueprinted it and said they checked the clearances and all was fine. I asked if it would happen again as they had not found the cause, the owner of the business said that he would personally guarantee that the car would not be back on a flat bed a month later with the issue. Well he was right, it only took 9 days and about 1200 miles. I was driving on the motorway and heard a big end start to knock so stopped the car and got it towed. In the rebuild they had not fitted an oil pump like I asked as they said they never fail

They stripped the engine down to find big end number 3 had no white metal left on it. So they blueprinted it again, we had an arguement and I ended up £500 lighter. Again they would not fit an oil pump

8 days later it went again, only 800 miles but this time it was clattering like the first time so while waiting for the truck I went on ebay and bought a complete engine which I got the garage to fit and I gave them no money.

So it should all be fine, well no. My car has done 30k since then, at about 20k it got a small misfire in the morning like the first engine had, then about 5k ago the head gasket failed on cyl 1, lots of water loss and huge back pressure. I got the local VX garage to change the head (I had a broken ankle so could not do the job myself) for a second hand one that was flat. I now have the low cyl pressure that comes back up a few seconds after starting it up

Where do I look for the fault, I am an ex Vauxhall mechanic with many years of experience so know about cars but I am stumped. The problem I assume is either the rings are sticking when cold or the valves are stuck open or closed due to hydraulic lifters not being up to pressure. Don't think it is the lifters as there is no top end noise just a horrible misfire

[rossko]

Don't think it is the lifters as there is no top end noise just a horrible misfire

To cause a compression loss, i.e. valve(s) stuck open, the lifters would need to stuck "on" so that gap was non-existant .... so there would be no noise.

Bearings run out, potentially sticking lifters or valve stems or gummed rings ... has anyone considered the oil type you are using?

[jalfrezigazee]

An interesting thought, I have 2 Vauxhall turbo cars running the same oil, one has 172k on it with no problems attributed to the oil but it is pretty much worn out and this one that has repeatedly broken down. I have been using genuine Vauxhall oil that is bought in 5 litre cans. It is a semi synthetic oil and has the correct spec, but who knows what is in a can marked Vauxhall. I will change to Shell Helix or Mobil 1 and see how it goes

[john_d]

did you get the vauxhall oil from vauxhall? i would have assumed they'd asked for your reg or what car you have to make sure you get the correct grade?

[demonicwillow]

Perhaps blocked oil delivery in the block somewhere or oil pressure relief valve jammed open !! have you had the filter or the filter mounting assembly changed and there is a trapped seal somewhere thus preventing lubrication of the top end maybe ?? does sound oil related though. can you connect an obdII reader/scanner and read live data for the oil pressure over a distance ?? you may have a major pressure loss when up to temp but not enough to flag up the lamp or MIL.

[demonicwillow]

Does your engine have piston cooling nozzles/jets which spray oil over a certain rpm to cool/lubricate the piston skirts ?? a blocked gallery or oil pressure loss would probably prevent oil delivery to these and above ie to the cam/head assemby's especially if your doing motorway miles.

[jalfrezigazee]

did you get the vauxhall oil from vauxhall? i would have assumed they'd asked for your reg or what car you have to make sure you get the correct grade?

Yes I got it from the dealers where I used to work, it is the correct grade for the engine, it is semi synthetic 10w40. We have found that if you run the fully synth the oil seals in the turbos leak at a low mileage so loads of us use this oil

Perhaps blocked oil delivery in the block somewhere or oil pressure relief valve jammed open !! have you had the filter or the filter mounting assembly changed and there is a trapped seal somewhere thus preventing lubrication of the top end maybe ?? does sound oil related though. can you connect an obdII reader/scanner and read live data for the oil pressure over a distance ?? you may have a major pressure loss when up to temp but not enough to flag up the lamp or MIL.

But why has it done it for 2 different engines. When we changed engines it was a complete setup with the filter mount changed as well. There is no sensor in the opil system to monitor unfortunately, i could buy a gauge though and monitor it

Does your engine have piston cooling nozzles/jets which spray oil over a certain rpm to cool/lubricate the piston skirts ?? a blocked gallery or oil pressure loss would probably prevent oil delivery to these and above ie to the cam/head assemby's especially if your doing motorway miles.

Yes it does have cooling jets which run constantly. Annoyed because when we changed the complete lump I was hoping it would all be sorted.

[demonicwillow]

I just popped over the shop to acquire a bottle of Danoff vodka (wicked stuff that is ) and realised that my suggestions were a bit pants cos of the engine change so its back to the previous suggestions of in-correct oil, or, an ancillary that was used with the previous engine such as an oil cooler which maybe blocked or restricted. 295 bhp !! what engine is in that ??

[jalfrezigazee]

Z20LEH Vauxahll 2 litre turbo, my Zafira has a Z20LET Vauxhall 2.0 turbo that makes the same power but not on LPG

[classicswede]

Did you reuse the petrol injectors? I have come across leaking petrol injectors that will cause a misfire and then lead to wearing out a cylinder. I have once had a problem with a ecu (on a V8) that was holding 2 petrol injectors open and killed a engine. Very rare thing to happen but possible.

[jalfrezigazee]

yes all the bolt on bits were re-used, that thought was running through my mind this week one morning while driving to work. A new set of petrol injectors are nearly £300 so will see if I can get hold of some used ones

[sportston]

Listen to demonic willow. Clogged oil cooler or clogged oilways in or to the turbo. That would be the first place I would look. Get a new oil pump because if it wasn't knackered before it will be now. Check for stuck injectors but I doubt that is your problem. You can get petrol injectors tested or reconned relatively cheaply. Try this guy on ebay http://www.ebay.co.uk/itm/380072659398 you can get a report and even ask for a video of your injectors before and after.

[Gilbertd]

Might also be worth having a chat with dannyf, he seems to know his stuff when it comes to VXR motors http://www.lpgforum.co.uk/viewtopic.php?f=32&t=10245

[rossko]

I think a lot of this speculation is about your original failure, which may or may not have anything to do with the current engine. I'm not sure how a leaky petrol injector would cause low cold compression when no wear was found at the (previous engine) rebuild, but that does not mean the current engine hasn't bore/ring wear. More cold test but with the spoonful of oil business required?

As I understand it's done 30K on a previously used engine (total mileage for that?), it had a headgasket fail and a "new" used head was fitted. Where from - not your original head back perhaps?!

The worry now is the morning misfire irritant, with the fear it may become another big end failure.

Are these engines prone to tight valve stems, like the early K-series or summat?

[billynoband]

Does anyone really rebuild engines anymore? Too complex, gaskets too expensive. Scrap yard engines are more reliable,

[classicswede]

This reminds me of a problem we had with my brothers turbo transit. 3 engine all killed a main bearing. Now my brothers transit is no normal van with the boost turned up to 18psi and fitted with a good intercooler it is one big quick oil burner.
The problem did turn out to be the oil over heating with the engine is under high load towing. Fitting a oil cooler in his case looks to so far have resolved things.

Oil temprature/flow is where I would think you need to be looking.

[john_d]

Does anyone really rebuild engines anymore? Too complex, gaskets too expensive. Scrap yard engines are more reliable,

older ones hell yeah, new engines i wouldnt think so but you never know.

[jalfrezigazee]

done the indecent thing and have arranged a trade in, it is the first car I have ever traded in, normally run them until they die but have had enough with this one

Getting another VXR so have started stripped all the modded parts off it and will be fitting them to the new car. LPG system is coming off on Friday and will go onto the newer motor,

Thanks for all the replies, I have been looking at so many things on the car and have decided to chuck in the towel, it will probably end up being broken for parts and ending up on ebay so it will go to help a few people

To answer about rebuiling engines, the one I have is hardly ever seen in a scrap yard and there are no exchange engines available so they have to be rebuilt. Have rebuilt many an engine myself. Will be doing my Zafira one soon, it is completely worn out so in need of a rebuild.

Swede, that is a fair bit of boost for an oil burner, my cars run at overboost 28psi then constant 21psi for the rest of the time