Advice for engine rebuild sought - not sure what's best.

[aclwalker 3]

I have a high mileage VR6 (190,000 miles) which I think is going to need some engine work done soon. The immediate concern of mine is the timing chains as I'm starting to hear the marbles-on-metal-tray sound I think, although it's hard to tell for sure.

 

I also have quite heavy oil usage. I don't have any leaks. It's hard to say how much oil I'm using but it's probably just within the 1 litre per 1000km (625 miles), but I fill it up from half way to the top of the dipstick because it makes the engine noticeably quieter to keep it in the top half of the dipstick. Half way mark to the top mark is half a litre, I believe, so I probably put in half a litre per 500 miles at a very rough guess.

 

I definately have oily cylinders. All spark plugs I take out have a coating of oil right up the threads and on the hex part and sometimes on the ceramic part too. Cylinder 6 (bottom right when facing engine bay (is this 6?)) is the worst and the spark plug is often very dirty. Cylinder 1 is quite bad too. All other plugs are nice and clean and dry on the combustion part but oily on the threads. I did wonder if I had oil leaking past the cylinder head gasket and falling down these channels.

 

I used to have a problem with hesitation that was solved with a new blue temp sensor and camshaft position sensor. Before I replaced these I had to periodically swap plugs 5 and 6 so that it would get cleaned up in the good cylinder, because it would get so bad it would stop firing altogether. This has not happened since I replaced the temp sensor and camshaft position sensor, although my mileage has dropped drastically since changing job and no longer commuting.

 

I don't detect blue smoke, either from blipping the throttle or on coasting or on startup. On cold days there is white smoke during heatup but I really think this is just remaining water in the exhaust. It goes away once the engine has heated up.

 

People used to say I had a 'grey' smoke when driving behind me. I have not heard of this since I sorted the temp sensor and camshaft position sensor so I believe this was simple poor mixture due to the engine management going into emergency mode during the hesitation.

 

The previous owner I'm sure said something about chains being done around 100,000 miles but he wasn't too sure about it, not being particularly technically minded. I think he ran the car low on oil, because he did talk about oil lights coming on and then topping up. (I think this was after I bought it!!)

 

I'm not sure what to do now.

 

I think I need to get the chains done and probably get a new clutch too as it's chattery and juddery when the engine is cold (like my old Golf was) and I believe this needs to be removed anyway when doing it.

 

But, should I investigate the oil problem in cylinders 1 and 6? Is this opening a can of worms? If I take the head off and recondition it then I'm as well checking the bottom end am I not?

 

Does it sound like a full recondition job?

 

I am technically competent and have done many successful repairs on this car and other VWs. I have access to a good range of tools and don't hesitate to buy them when needed. I have never done engine rebuild work myself before, however.

 

Should I attempt a head rebuild myself? I have the help of my dad too, who is technically competent in the same way and I have the advantage that I don't need the car for work.

 

Is there any point in doing a head rebuild without touching the block on a 190,000 mile VR6? I don't think it's ever had the head off before.

 

Should I just do the chains and clutch myself and put up with the oily cylinders for now? The car runs great at the moment with none of its previous hesitation. It's just the chain-like noise that worries me.

 

I've lost an engine before on my old Golf through water pump seizure stripping off all the teeth of the timing belt and causing catastrophic engine damage, so I don't want a repeat of that experience in this far more expensive engine.

 

I remember reading about a great price for a new/reconditioned engine direct from VW (but I can't find it for love or money using the search in this forum) which seemed to suggest that rebuilding was pointless due to the cost. Is this a better option? Swapping the engine for a new or already rebuilt one?

 

I'm not really sure what to do and would appreciate any advice or suggestions on where to go from here.

 

For the record, I am not interested in mods or power increases, I just want a standard car that runs well with reasonable costs. I don't want to scrimp on costs if it will cause problems in the long run, but equally I don't want to spend huge sums unnecessarily.

 

Any help gratefully appreciated...

[dr_mat 0]

1) oil on plugs - almost certainly this is the cam cover gasket. It's quite common for this to seep down onto the plug threads.

2) oil on the plug CONTACTS is more likely to be oil leaks internal to the cylinders - primary concern would be the valve stem seals, less likely suspect is bore/ring problems.

3) water pump can't take out the cam chain, cos it's not connected to it

4) the great price for the new/recon engine wasn't real. Forget about it, it's £4k+.

5) whether it's worth getting the head recon-ed again is up to you. It's not much labour to pull the head off and inspect the bores, and leak down and/or compression tests can give hints as to the condition of these parts of the engine.

 

Was there anything I missed...?? :)

[Scruffythefirst 0]

If its working right then once you start taking an engine of that millage apart you're going to have to do all of it really as it'd be crazy to put old bits back in.

 

However, as you need the chains and clutch done I'd take the engine out, and strip it.

 

You'll then need to budget for a full gasket set, new rings, full set of bottom end shells, plastiguage (you'll also need a set of verniers to measure the crank journals), clutch and timing chains as a minimum. Your also going to need a light head skim and block reface and a rehone if the bores are in good condition.

 

If the bores are out of spec you'll need a rebore and new pistons / new block / second hand block. If the crank journals are looking worn you'll need a polish or regrind and possibly oversize shells - a good machine shop should be able to advise here. Depending on the state of the cams you may need new ones and new folowers. Valves should clean up but it'd be wise to replace any that look pitted, especialy exhaust valves. You should ideally have the machine shop recut or replace the valve seats depending on condition.

 

I'd budget £150-£300 for machining plus the costs of parts. If the bores are really shot (and it sounds like they may be - excessive oil usage) then it may be cheaper to get a second hand low millage engine and put that in. If you take the head off you should be able to get an idea of the state of the bores as if they are badly worn there will be a thick ridge around the top of the cylinder - scrape the carbon off first.

 

However, if theres no rush then you can take the engine out, strip it and then decide what to do.

[aclwalker 3]

1) oil on plugs - almost certainly this is the cam cover gasket. It's quite common for this to seep down onto the plug threads.

2) oil on the plug CONTACTS is more likely to be oil leaks internal to the cylinders - primary concern would be the valve stem seals, less likely suspect is bore/ring problems.

3) water pump can't take out the cam chain, cos it's not connected to it

4) the great price for the new/recon engine wasn't real. Forget about it, it's £4k+.

5) whether it's worth getting the head recon-ed again is up to you. It's not much labour to pull the head off and inspect the bores, and leak down and/or compression tests can give hints as to the condition of these parts of the engine.

 

Was there anything I missed...?? :)

 

Thanks for the responses.

 

I did wonder about the cam cover gasket.

 

Is it possible to do a compression and leak down test myself. Is the equipment expensive? How much should I expect to pay for someone to do it?

 

Thanks.

[Kevin Bacon 5]

1) oil on plugs - almost certainly this is the cam cover gasket. It's quite common for this to seep down onto the plug threads.

 

It's more likely accumulated oil spillages from previous oil changes that's worked it's way down into the spark plug threads over the years. The ribbed rocker cover gaskets are actually very good if torqued down to spec.

 

2) oil on the plug CONTACTS is more likely to be oil leaks internal to the cylinders - primary concern would be the valve stem seals, less likely suspect is bore/ring problems.

 

It is likely to be the bores imo. The sort of consumption he's talking about and the fact plugs 1 and 6 are wet is a sure sign of that. You can even shine a torch onto the piston crowns when at TDC to see if they're wet if you want to be really sure.

The guides tend to wear evenly across the 6 cylinders.

[aclwalker 3]

It is likely to be the bores imo. The sort of consumption he's talking about and the fact plugs 1 and 6 are wet is a sure sign of that. You can even shine a torch onto the piston crowns when at TDC to see if they're wet if you want to be really sure.

The guides tend to wear evenly across the 6 cylinders.

 

Kev,

 

I have actually done that with a torch with 6 and it was indeed wet. Sh*t! Sounds quite serious now.

 

The thing is that it runs really well now and just has slight fluttering on idle. I manage 27mph on 10 mile journeys, even in the 30s if I take it really easy.

 

Maybe the thing to do is to just fix the chains and clutch myself and forget about the rest for now if it really is that terminal. My mileage is only 4k per year (if that) at the moment.

[Scruffythefirst 0]

The thing is that it runs really well now and just has slight fluttering on idle. I manage 27mph on 10 miles journeys, even in the 30s if I take it really easy.

 

 

My mums BMW had the infamout Nikasil problem and was using a litre of oil every 250 miles. Still drove fine and idled reasonably well. A compression test is easy to do yourself and should show low readings on 1 and 6. Important thing with compression test is that you do it at WOT and when the engine is hot. Theres no way to know how much the bore has worn without taking the head off / engine out.

 

It seems pretty silly to spend the money on the clutch and chains, not to metion the effort to stick a knackered engine back in. You may get away with just a rehone and new rings - certainly on 2-5 i would have thought. I'm not sure if 1 and 6 can be sleeved or if it'd be cheaper than new pistons / block.

[Kevin Bacon 5]

I'm with scruffy, I wouldn't waste money on a head and chain job for a knackered block personally.

 

It may just be you oil control rings mate which is contributing to the oil consumption, but the compression rings are prob still OK. A leak down test will tell for sure. This test blasts compressed air into the chambers and the air pressure 'lost' is measured and calculated to give a PSI reduction per cyl. Most experienced testers can actually hear where the air is leaking from too, i.e. through the guides or through the rings....or both, perish the thought.

 

Oh and mine's heading the same way too as my 1 and 6 are wet too, so I sympathise.

 

I'm not planning on A) sticking with the car for much longer, or B) sticking with the 12v engine if I keep the car, so I'm not bothered!

[aclwalker 3]

Scruffythefirst,

 

What's "WOT"? I'm also interested in your comments re sleeving. I was under the impression that one of the differences between the 2.8 and 2.9 was (apart from obvious displacement differences) that the 2.8 was sleeved and the 2.9 wasn't. Are you saying that it might be possible to sleeve an 'ovaled' cylinder?

 

I totally see where you're coming from with the 'no point in fixing stuff on a bad block'.

 

 

kevhaywire,

 

I had totally forgotten that there are two types of ring, compression and oil control. Are you suggesting that it's possible that I just have an oil control ring problem but good compression rings? Would this also mean I could have good bores too? If a compression/leak down test could confirm this then would that be good news in the sense that I could safely START on a full rebuild in the knowledge that the bores are likely OK?

 

I guess I'm saying, "Is there a possibility of still having duff bores, even if a compression test shows everything as being OK?".

 

Thanks again for all your prompt answers.

 

Alan

[Scruffythefirst 0]

WOT = Wide open throttle

 

Are you saying that it might be possible to sleeve an 'ovaled' cylinder?

Maybe, I don't know enough about the VR6. Best bet would be to ask a good machine shop. It may end up costing more than a replacement second hand block / engine.

 

Are you suggesting that it's possible that I just have an oil control ring problem but good compression rings? Would this also mean I could have good bores too?

 

 

Possible, but i wouldn't bank on it. If its only the oil control ring thats bad then yes you could have ok bores. However, the chances of breaking 2 oil control rings on the two cylinders that are known for bore wear is low.

 

There is no way of knowing the state of the bores without measuring them accurately. You may have good compression and still need a rebore althought its unlikely. A rebore isn't a problem untill you have to take so much out you need oversize pistons....

[Kevin Bacon 5]

Yeah you can't sleeve a VR bore as it's an iron block.

 

The problem with the 2.9 is it's overbored from the factory, so to rebore your 2.9 block means you need to go out to 3.0. If you want to stay with 2.9, you need to get a 2.8 block bored out to 2.9. Sounds bizarre I know, but that's the state of affairs with VRs I'm afraid.

 

IIRC, 2.8 bore is 81mm, 2.9 is 82mm and 3.0 is 83mm, the limit of the block apparently. Someone will correct me if that's wrong.

 

As scruffy says, you may be lucky in that just the Oil rings are worn but 1 and 6 are known weaknesses for bore ovalisation I'm afraid.

[samm_cvr6 0]

I just got my cylinder head reconditioned but to be honest, in hind sight I would of bought the 2.8 24v v6 I was offered for £450, it's just at the time, none of the mechanics I talked to were interested in fitting it for me. I even offered one of them £1k to do it. Like the others say, I would either spend as little as possible, or get shot of it and get a C with less miles. Just a thought.

[Scruffythefirst 0]

Yeah you can't sleeve a VR bore as it's an iron block.

 

 

You can definately sleve an Iron block, as cossies sometimes have it done. However, the cyl walls on the vr are thin as it is, so there may not be enough room.

 

Are the rest of the 2.8's dimensions the same as the 2.9? If so a second hand 2.8 block should only be £200 max i would have thought. And then you just take it to a machine shop and get them to bore it to the exact tollerance for your existing pistons - you'd then end up with a brand new engine that will last another 200k

[aclwalker 3]

Thanks for all the responses. I'm currently researching a bit more on the subject and I'll try to do some investigations at the weekend...