Gti6 Goes Pop! 2

[nick9one1 2]

Well I started on DrSartys gti6 today.

 

History;

for the 3 months I had been driving the car ran absolutely fine, no problems other than needing a small amount of maintenance (brake pads etc). The engine ran quietly, never tapped, and pulled well. No symptoms of a 'tapper' or any other mechanical fault.

 

Then one day about 100 yards or so from work, while slowing it suddenly started tapping loudly from the head.

There was no previous warning and the car had been driven at a constant 60mph for about 15 minutes prior. Oil was good, water was good and the engine wasn't over heating.

 

I had a mechanic come to look at the car and he said it was definitely tapping from the head but couldn't saw why without disassembly.

 

I had the car towed home and checked everything; the belt appeared to have slipped.

 

 

Me and Rich decided a replacement head was the best route forward so Rich organised the old one to be traded in against a recon with Mechanical_Repairs (C.G. Cars Leicester)

Went down there on Saturday and they were a great! Carl certainly knew his stuff.

 

 

Today;

I started by taking the sump off as a damaged piston needed to be replaced. This took longer than I expected but got there in the end!

The old piston

Replaced by one Carl gave me

 

Then started taking the old tensioner and pulley off to replace with the ones from the new kit and behold..

the tensioner was covered in oil.

 

Looking at the back and side of the block it appears that oil had been slowly leaking from the head. Making its way onto the belt and the tensioner. Resulting in a sipped belt.

All four pistons had fresh marks from the inlet valves on them so there is no doubt in my mind that the belt had slipped and was caused my head gasket failure.

 

I cleaned up the block, and fitted the head, gasket, pulley, tensioner and belt. then all timed and tightened up.

 

Another hour or so of work left but not bad for a Sunday!

[EdCherry 34 1 Cars]

Good days work, BUT pistons are meant to be replaced in sets rather than 1 of this set and that set, correct me if im wrong but this is what ive been taught.

[philfingers 5]

strange the oil caused it to slip, I would have thought it more likely to just fail. At least you know why now

[DrSarty 90 1 Cars]

Excellent work Nick, especially for one day!

 

As said: wish that hadn't happened; but it did and we've nearly got it sorted.

 

Ref the pistons: I'm sure a complete swap is ideal, in an ideal world (perhaps something to do with match-weighting - I really don't know), but a simple single piston swap was suggested by more than one person. So surely it can't be that bad an idea......can it?

 

Where was the oil leaking from the head? You mentioned the gasket but I didn't know of any gasket failure.

 

The light at the end of the tunnel is visible.

Edited August 3, 2009 by DrSarty

[nick9one1 2]

Well the piston does match, all the numbers inside are the same so I think it will be fine.

 

There was no water leakage and compression was fine so It wasnt total HGF. The HG had only failed in that one point, quite unusual I guess?

[Cameron 16]

I don't see why you'd need to replace them as a set, its not like the standard items are perfectly matched for balance, is it?

 

Bit worrying that you had marks on all pistons from the inlet valves! Have you had to replace all the valves? Surely it must have bent a few.

[hexhamstu 9]

I don't see why you'd need to replace them as a set, its not like the standard items are perfectly matched for balance, is it?

 

Bit worrying that you had marks on all pistons from the inlet valves! Have you had to replace all the valves? Surely it must have bent a few.

 

the whole head was swapped for a recon'd one. so I guess that includes valves as well.

[taylorspug 7]

I doubt the oil caused the belt to slip tbh. What was the belt tension like on the old cambelt?

[DrSarty 90 1 Cars]

I doubt the oil caused the belt to slip tbh. What was the belt tension like on the old cambelt?

 

I thought that too.

 

Yes Cameron: the info's in the thread matey, i.e. complete reconditioned head; we didn't use the old one at all.

 

When Nick took it to Carl it was confirmed that not only had the head received a poor (rough) effort at porting, it had been skimmed to within 'an inch' of its life.

[Chuckyd 0]

Total shame but a good looking car

[jas-E 1]

I don't see why you'd need to replace them as a set, its not like the standard items are perfectly matched for balance, is it?

 

Pistons are usually replaced in sets as you know they roughly have the same amount of bedding in if from previous running. If you replace one piston for a new one in an engine that has done 60k miles, then that piston will see higher friction than the rest which have bedded in nicely (hopefully!)

 

But if the running hours are roughly the same i guess its something you can get away with

[Cameron 16]

the whole head was swapped for a recon'd one. so I guess that includes valves as well.

DOH!!!

Sorry I must have still been asleep.

 

 

Surely having one piston with slightly higher friction is going to be barely noticeable though.

Edited August 3, 2009 by Cameron

[Miles 331 1 Cars]

You need to check the piston size's really as there's around 3 size's much like the Mi engine's etc so the clearance will very much depend on this, Changing the odd piston isn;t the best pratice but it can be done, The main issue is the Ring's re-seating in the bore from the old Piston and Ring's

 

One thing I will say is your very lucky, every one I;ve had and seen with that damage has buggered up the bore.

[nick9one1 2]

Yeah, I was surprised to see the bore was completely untouched! all you could see are the swirl marks from the original honing?

[welshpug 1,657]

wouldnt imagine a single piston would be an issue if its the same size and fitted with new rings and the bores de-glazed.

 

even if you cam still see the homing marks you do need to check the size of the bores in case of excessive wear at certain points in the cylinder.

 

very lucky the bores and bottom end has got away unscathed, ust hope the rest of the car is worth spending all that money on the engine, I know someone with a similar age and mileage car that snapped its belt last week, as he has no facilities to sort the engine himself its not financially viable to fix it and it'll be broken for parts.

 

wouldnt imagine a single piston would be an issue if its the same size and fitted with new rings and the bores de-glazed.

 

even if you cam still see the homing marks you do need to check the size of the bores in case of excessive wear at certain points in the cylinder.

 

very lucky the bores and bottom end has got away unscathed, ust hope the rest of the car is worth spending all that money on the engine, I know someone with a similar age and mileage car that snapped its belt last week, as he has no facilities to sort the engine himself its not financially viable to fix it and it'll be broken for parts.

[philfingers 5]

you got a wee stutter there!

 

wouldnt imagine a single piston would be an issue if its the same size and fitted with new rings and the bores de-glazed.

 

even if you cam still see the homing marks you do need to check the size of the bores in case of excessive wear at certain points in the cylinder.

 

very lucky the bores and bottom end has got away unscathed, ust hope the rest of the car is worth spending all that money on the engine, I know someone with a similar age and mileage car that snapped its belt last week, as he has no facilities to sort the engine himself its not financially viable to fix it and it'll be broken for parts.

 

wouldnt imagine a single piston would be an issue if its the same size and fitted with new rings and the bores de-glazed.

 

even if you cam still see the homing marks you do need to check the size of the bores in case of excessive wear at certain points in the cylinder.

 

very lucky the bores and bottom end has got away unscathed, ust hope the rest of the car is worth spending all that money on the engine, I know someone with a similar age and mileage car that snapped its belt last week, as he has no facilities to sort the engine himself its not financially viable to fix it and it'll be broken for parts.

Edited August 4, 2009 by philfingers

[DrSarty 90 1 Cars]

you got a wee stutter there!

 

It's a forum thing; doing it every now and again.

 

I haven't said 'phew' yet until I've heard and seen a video of it running again...

 

It's cost around £500 to repair, but that's mainly parts and I'd have been screwed if I'd have had to pay labour charges, which makes perfect sense based on WP's story above. Probably would've had to break it, but I was determined to not let it die.

[jackherer 543]

It's a forum thing; doing it every now and again.

 

The forum concatenates consecutive posts by the same author if they are posted within a certain (short) time limit so if someone double posts they are made into one post automatically to keep things tidy until a mod spots it.

[DrSarty 90 1 Cars]

concatenates

 

?

 

OK. I need help now.

[EdCherry 34 1 Cars]

?

 

OK. I need help now.

 

 

Defined

 

I am now wiser.

[jackherer 543]

?

 

OK. I need help now.

 

merges, joins, combines etc

 

http://en.wikipedia.org/wiki/Concatenation

[nick9one1 2]

Right I’ve made some more progress!

 

got inlet and exhaust manifolds on.

ac pump

aux belt

exhaust bolted up

cam covers

spark plugs

coil packs

water pipes

water

oil

all plugs connected

turned it over loads of times by hand and it’s still timed up.

 

tried starting it, doesn’t seem to tap (at least nothing like before), but has a very rough idle

It was running ok before the belt slipped so I can’t really think what’s caused this.

 

I’ve checked all the connections are ok

TPS

ICV

MAP

Lambda

Cam Sensor

and a few others.

 

It’s almost like its miss-firing the engine shakes a fair bit back and forwards.

The only thing I think I can think of is spark plugs, I forgot to buy new ones and I’ve had to put some old ones from a XU10J4R in.

 

I have spare map and coil packs so can check those....

any ideas?

Edited August 5, 2009 by nick9one1

[DrSarty 90 1 Cars]

'Sounds' like it's running on 3 Nick. Good work so far.

 

I'd suspect plugs like you said, an HT lead (or COP) connection, or an injector not plugged in right.

 

It's probably something simple.

 

I'd try taking HT connections off to see which cylinder is not providing a proper power stroke, as one won't make a difference. You could do the same with the injector plugs.

 

Errrr.....I think you've covered most things, unless a coil pack has failed.

 

It should just work straight away, so we have to look at "what's changed?" and "what could I have put together incorrectly?". Is it possible to get firing order wrong on a sequential fuel and spark system? Probably plugs or a connection then IMO.

 

You'll find it.

[rubyna 4 1 Cars]

You seem to have coverd usual suspects, like Dr.S says check a coil pack aint failed, connections and new plugs..

Doesnt sound like anything too worrying..Good luck

[nick9one1 2]

thanks

 

just checked all the obvious but still does it.

 

i have noticed the MIL light is on though.. does that narrow it down?