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Model specific boards => Golf mk3 => Topic started by: Gti_Jamo on 28 June 2013, 17:13
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So basically i bought a replacement engine for my high miler as its burning oil quite bad and down on compression on cylinder number 6. Now i bought it off another forum and was told it was a good engine but noticed oil deposits on a couple of the inlet valve stems (more so on cylinder number 1) so decided to whip the head off for a better look. Now the heads been off recently as its been skimmed, it has new chains also. The exhaust valve in cylinder number 1 was badly carboned up as was the spark plug that came out of it. Valve guides look good. Just in the process of cleaning the head up and removing the carbon from the valves, new stem seals and lap the valves back in and the heads good to go.
The pistons are in good condition. However what concerns me is that all of the cylinders have a bit of a lip at the top that I can feel with my finger. All pretty much the same. Should this be a problem. Was told the engine only done 80k but I doubt that very much. I'm not prepared to go getting it rebored with oversized pistons or have to do any work on the bottom end whatsoever and would try and just source another one if its a big issue. The last thing I want is to build it all back up and fit it only for it to burn oil like my current one. I sat an inch of oil in each of the bores on top of the piston and the levels barely dropped over the course of 3 days.
What do you think? I guess I should have done a leak test on the engine before I began stripping it.
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it all depends on how big the lip is. seen plenty engines with a lip on the bores but running fine. that thing your doing with the oil in bores will give you a good idea of how even your cylinder wear is. I would try it again with atf as it will drain through quicker. its not an easy thing to measure without a bore gauge. you should take it to an engine builder and get them to measure it up just to be sure.
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i wouldn't say is huge be can be easily felt, more so on outer edges but that would be normal i guess. I'll test the cylinders again and see what happens and take it from there. I'm hopeful that because its even wear I can put the oil on the valve stems down to the stem seals or the guides. I done a rough test on the guides by checking the latteral play in the valves and its not much but waiting on my digi gauge coming to get some accurate measurements.
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You have a lip you so you have wear.
Measure the gap with feelers at room temp, dia of piston and bore as well. you should be able to find the tolerances somewhere ont net, let that be your guide.
How much has it worn over 80k vs how much metal is left in the tolerance band between piston and bore.
I have got away with new rings before but that can be a can of worms in itself :grin:
I am not 100% on VR valve guides and geometry, but at about £100 a set it will give you piece of mind
What sort of gauge have you bought?
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yeah when you have a lip you have wear but you can get away with a little. all depends what your plans are with engine and what kind of mileage you want out of it. what I would do if I was you would be to take the head of the engine in the car(assuming it aint a daily ) and compare the bores to your new engine to see which is best. could be the head that's bad on the car. and if that's so then you could just put the head you cleaned up straight on to car engine. get a leak down test done on car engine and that will confirm if its bad cylinders or a bad head.
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Sorry for the delayed reply.
You have a lip you so you have wear.
Measure the gap with feelers at room temp, dia of piston and bore as well. you should be able to find the tolerances somewhere ont net, let that be your guide.
How much has it worn over 80k vs how much metal is left in the tolerance band between piston and bore.
I have got away with new rings before but that can be a can of worms in itself :grin:
I am not 100% on VR valve guides and geometry, but at about £100 a set it will give you piece of mind
What sort of gauge have you bought?
The gauge I got isn't suitable for measuring the bore wear unfortunately. I will check with feeler gauges though if i can find tolerances. Ive measured the valves and the lateral play in the valve guides and all appears to be decent enough.
yeah when you have a lip you have wear but you can get away with a little. all depends what your plans are with engine and what kind of mileage you want out of it. what I would do if I was you would be to take the head of the engine in the car(assuming it aint a daily ) and compare the bores to your new engine to see which is best. could be the head that's bad on the car. and if that's so then you could just put the head you cleaned up straight on to car engine. get a leak down test done on car engine and that will confirm if its bad cylinders or a bad head.
My car is currently a daily so have planned for a quick change over. Have already done a leak down test on the engine in the car and its definitely leaking past the rings on cylinder number 6 and is way down on compression on same cylinder. My plan is to more than likely sell or swap the car once the engine is changed and is running perfect as this is the last job on the long list I had when I first got it and will be worth decent money when finished. I have a Mk2 I want to get started.
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I would say thats a rebore job mate!
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I would say thats a rebore job mate!
Well that will not be happening lol....I might take my chances on it. Depending on what the feeler gauge test says. I must also add that the wear lip is more apparent on outer edges but i guess thats normal given the configuration. Will be a slight ovalisation in that case.
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I would get a second opinion from an engine rebuilder. the bores might not be past it yet. to measure piston to bore clearance you really need the rings out and you know what that means???
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There should be no leaking past the rings!
= rebore
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you will get a very slight leak past the piston ring end gaps but that cant be helped. you may be able to measure the top ring end gap with a very then piece of wire and a vernier caliper just to make sure its not outside tolerance.
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I will more than likely take my chances and build it back up. Like i said barely any oil escaped past the rings. I sat an 25mm of oil in them and the had dropped to about 22mm over 3 days and had no further loss after that. No way its getting rebored as cant afford that right now. If it turns out oil is getting past the rings then will just change the bottom end.
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yeah a rebore is big bucks eh. maybe the 80k mileage is genuine. I mean if the head is in good order and it was a vw head gasket (showing it probably hasn't been split before). then the bottom end could be sound. did you scrape carbon of lip on bore? I find a scotchbrite and wd40 just right for doing that and cleaning piston crowns.
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Yeah i used exactly that to clean the lip. The pistons look mint and that without cleaning them. Only a bit of surface carbon. I dunno if i mentioned but the head has been off very recently as its been skimmed and gasket did not look bad at all. Brand new chains also so someone had faith in it at some point recently to do the work. The guy wasnt the owner bet getting rid for his mate. He said it came out because of a 1.8t conversion and said it was a strong engine.
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have a good look at the cylinder walls to check for any scoring. if there is none then I would take a chance with it. I had a 2.0 audi 3a block once with 172k on it. there was a slight ridge on the bores but I stuck it in my mk2 golf anyway and it ran mint. pulled really well and wasn't bad on oil at all.
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Having a rebore to 83.5mm and am being charged £86.00
So its not big bucks!
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Having a rebore to 83.5mm and am being charged £86.00
So its not big bucks!
Why so much? Surely bigger pistons will be needed being 2.5mm larger or do new rings take that up? Did your bores have a lip and did you measure the wear? Looking at my bores again, with the lip being original diameter the wear isn't too bad. No scoring of the cylinder walls from what I can see and feel.
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And here was me thinking £86 was dirt cheap! Is round my way!
Only reason I am having a rebore is to increase the capacity to 2.1 litres (2092cc) with a diesel crank 95.5mm throw.
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And here was me thinking £86 was dirt cheap! Is round my way!
Only reason I am having a rebore is to increase the capacity to 2.1 litres (2092cc) with a diesel crank 95.5mm throw.
No I meant why so much material removed. But thought you were on about a vr engine.
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He's doing an ABF engine.
It might be worth re ringing the block after Honing with a flexhone. It doesn't necessarily need a rebore as rings can wear faster than the block. A bore micrometer can show you how much wear.
Flexhones are fairly cheap off eBay and you can do it with a drill and some paraffin.
Then put some new rings in and that should give you some peace of mind.
You will have to run the engine in to bed the rings in though
My engine had a slight lip at 123k but when measured it was only 0.03mm and was well within wear limits.
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It might be worth noting you cant use a standard ring compressor on the vr engine
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He's doing an ABF engine.
It might be worth re ringing the block after Honing with a flexhone. It doesn't necessarily need a rebore as rings can wear faster than the block. A bore micrometer can show you how much wear.
Flexhones are fairly cheap off eBay and you can do it with a drill and some paraffin.
Then put some new rings in and that should give you some peace of mind.
You will have to run the engine in to bed the rings in though
My engine had a slight lip at 123k but when measured it was only 0.03mm and was well within wear limits.
Well thats all mine has, slight lip across the range but more apparent on the outer edges. Just by feel. Like I dont need the engine to be perfect, just better than the 190,000 mile one I have now. Its dying more with every run. Don't have the money to do much to the bottom end.
It might be worth noting you cant use a standard ring compressor on the vr engine
Yeah I read that. Doubt i'll remove pistons though.
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Well the engine is built back up and fitted over weekend. Sounded rough and was real smokey on initial start up but after 10 mins it sorted itself out. Used the inlet manifold from my bad engine and would have had some traces of oil from the excessive crank case pressure caused by the bad rings. Anyway despite my new engines bore lips it runs like a dream, compression test showed 165psi across the range give or take a few psi. No smoke on start up, accelerating or overrun. Hydraulic lifters and chains are quiet. The car feels much quicker. Everythings top notch so i'm happy.
Will update my dub rides thread with pics when i get time. Cheers for the advice.
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How did you do the compression test? warm? full throttle? Sounds a bit low. Although if they are equal it should be fine.
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Remember folks
The Tshirt Knows... How to Diagnose...
:wink:
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I may have spoken to soon unfortunately. Some more info to follow. :cry:
And yeah compression test was done up to temp with open throttle. Cranked 6 times.
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Ok then,
So anyway got it fitted and running and ran as sweet as a nut, no smoke. Nice and quiet. Pulls really well compared to my old engine so was really happy that I have a strong one.
However after running it for 100 odd miles I noticed a wee bit of blue smoke on overrun that gradually stated to get worse as the journey continued. Was gutted!! Basically its not until the throttle is closed then I start to smell the oil building up then once I get back on the throttle the smoke is released. Yesterday morning I had a wee bit of smoke on start up but nothing this morning and never started to smoke until it was right up to temperature. Does not smoke driving normally, only when throttle is closed for a period of time.
So this afternoon I done some tests first being another compression test. This was a hot / dry test and the results are as follows.
Cyl 1 - 164psi - No oil on plug
Cyl 3 - 165psi - No oil on plug
Cyl 5 - 162psi - No oil on plug
Cyl 2 - 165psi - No oil on plug
Cyl 4 - 168psi - No oil on plug
Cyl 6 - 175psi - Oiled up plug
With number 6 being higher and oil on plug I turned the engine over with the plug removed to clear any oil and ran the test again on that cylinder and it gave me 162psi so all pretty level and not particularly low.
Then I done a leak test on each cylinder at tdc. Pumped 6 bar into them and could hear a slight hiss from the oil cap on each cylinder, none anymore worse than others. Would a slight seepage be normal? I would think it would be.
Put the car all back together, took it for a 20 mile blast and got a tiny bit of blue smoke on one occasion despite me letting it coast down a big hill in 5th I couldn't get the smoke to appear nor could i smell it building up. It makes no sense considering yesterday I done the same thing on the same road and i could barely see behind me from blueness. I know when the blue smoke is going to appear as i can clearly smell it before I get back on the throttle.
So what do you guys think. A worn bore or ring? If so should it of not been smoking since its first ran? Duff stem seal perhaps. Or something i'm not aware off. The seals I got came with the headset and more or less just pushed on the valve guides pretty easy. I know I should of went to vw for them. Its just strange how it appears to be intermittent, usually engines either burn oil or they don't, not sometimes, like mine appears to be doing.
Just need to know where to begin. I don't mind removing the head again and doing the stem seals as its no big job but don't particularly want to do it if its not going to fix the problem. As for the bottom end, well I don't really have the money to start getting that redone. I'm a vr6 novice so not too clued up on these problems. My old engine smoked in a similar fashion but done it all the time and was way down on compression in cylinders 1 and 6 and was about as slow as my old 8v but this engine goes really well despite this problem. Put the smile back on my face anyway.
So in my opinion its either the seals or the rings/bores but would like to believe the seal on cyl 6 has had it or i damaged it when fitting. Or it could because they are cheap and nastys. I should of put proper ones in, I hold my hands up for that error.
Sorry for the essay, just want to give as much info as possible.
Give me your knowledge. Cheers
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yeah its probably only smoking when its up to temp as that's when the oil is thinnest and can be drawn down the guide. maybe one of your seals has came loose or maybe it was damaged on fitting? did you by any chance distort the top of the valve guide when pulling the old seal off? them seals can be darn tight! doubt its your piston rings though.
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yeah its probably only smoking when its up to temp as that's when the oil is thinnest and can be drawn down the guide. maybe one of your seals has came loose or maybe it was damaged on fitting? did you by any chance distort the top of the valve guide when pulling the old seal off? them seals can be darn tight! doubt its your piston rings though.
Hi mate, yeah but its strange how it never smoked bad on my journey home. It was upto temp and should of done it on request almost. Was really carefull removing seals and the new ones seated will with little force. Usually the seals are quie tight to go on from experience with other engines. Maybe a problem with the head gasket or a head bolt near cylinder number 6. A crack between cylinder and oil chamber. All have crossed my mind. I wish I could rule out the ring/bore wear but I cant properly check it just by looking at it. But visually it looked ok. No different to the rest. Also it wouldn't have taken 100 miles for the problem to arise if it was already there. But, thinking back, when cleaning the valves that exhaust valve on 6 did have a little more burnt on carbon compared to the others. Not much though.
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Remember folks
The Tshirt Knows... How to Diagnose...
:wink:
:laugh:
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Remember folks
The Tshirt Knows... How to Diagnose...
:wink:
:laugh:
Diagnose this please.... :wink:
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Did you do a wet compression test?
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Did you do a wet compression test?
No but only because i had nothing suitable to drop some down but will get one done. I take it i should be looking for an even rise in compression?
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It will rise, but if its alot then it should point to rings. It seems like i could be the stems though, or you could have worn valve guides causing excess movement on the seals. Can't remember what you did regarding head. Is it the original?
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I believe so...i checked the play in the guides and were within tolerance but there was wear there. Best just get them done when the heads off though.
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I would say you have a stem seal or valve guide problem tbh.
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its a bit of a runt that eh. having to strip it again. maybe there is oil getting in from chain area. which might explain the previous head skim. I would check the surface of the block in that area very carefully for some kind of damage/crack. but check the stem seals on that cylinder first before you pull head. maybe the seals had come off before you bought engine and then it could have happened again now.
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I dont mind taking the head off again as it easier than pulling the engine out. Its just the money i need to spend on parts and fluids again. But ive come this far with it i'll get it done. Funds ain't great, but thats only because i spend it all on fuel and oil. With the inlet manifold off, by rights i should see traces of oil on the inltet valve stem. That will be the first thing I take off. But i'll monitor it over the next few days. I've got the dash to take out once this is sorted as the foam on my heater flaps keeps hitting me in the face. After that i've more or less got a perfect mk3.
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I believe so...i checked the play in the guides and were within tolerance but there was wear there. Best just get them done when the heads off though.
Not sure how the vr6 guides and stems are but at120K on my ABF there was alot of movement of the exhaust valves when checking mine half way down the valve. Had to replace all 8 exhaust guides. Also when fitting stem seals i had to puish them on hard with a 10mm socket.
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I dont mind taking the head off again as it easier than pulling the engine out. Its just the money i need to spend on parts and fluids again. But ive come this far with it i'll get it done. Funds ain't great, but thats only because i spend it all on fuel and oil. With the inlet manifold off, by rights i should see traces of oil on the inltet valve stem. That will be the first thing I take off. But i'll monitor it over the next few days. I've got the dash to take out once this is sorted as the foam on my heater flaps keeps hitting me in the face. After that i've more or less got a perfect mk3.
lol that darn foam. I always used to wonder where that was coming from on my old mk2. until the heater stopped blowing hot and I discovered the really bad design of the flaps inside the heater box. yeah if you have oil on the inlet valve then you can be pretty sure its coming down the guide. but the petrol would wash a lot of it off. why don't you just rebuild the head off your old engine and fit that? maybe clean out the ports a bit while your at it.
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I dont mind taking the head off again as it easier than pulling the engine out. Its just the money i need to spend on parts and fluids again. But ive come this far with it i'll get it done. Funds ain't great, but thats only because i spend it all on fuel and oil. With the inlet manifold off, by rights i should see traces of oil on the inltet valve stem. That will be the first thing I take off. But i'll monitor it over the next few days. I've got the dash to take out once this is sorted as the foam on my heater flaps keeps hitting me in the face. After that i've more or less got a perfect mk3.
lol that darn foam. I always used to wonder where that was coming from on my old mk2. until the heater stopped blowing hot and I discovered the really bad design of the flaps inside the heater box. yeah if you have oil on the inlet valve then you can be pretty sure its coming down the guide. but the petrol would wash a lot of it off. why don't you just rebuild the head off your old engine and fit that? maybe clean out the ports a bit while your at it.
Its an idea, gonna whip that head off soon. On a brighter note I put some deisel down number 6 and left it over night then cranked it out and it not smoking so far but will keep an eye on it and monitor oil consumption. Car broke down the other day shortly after driving through some water. Turned out the oxygen sensor had died but luckily had a spare.