engine bores,liners and overall condition advice

daz-20vt

daz-20vt

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hi guys
so my car is meant to finally being started early next year for the head gasket issue prawn spitefully caused.

I had fuel in the coolant which led my mechanic to come to this conclusion.
but since this others have mentioned cracked liners, oval bores and piston rings.

how do I go about confirming this?
before I go ordering bits I may not be needing. any help as always is very welcome!!!!
thanks!!!
 
lol
I've no idea but would LOVE that to be true!!!!
 
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<tuffty/> said:
No liners on a 1.8t block

<tuffty/>
Click to expand...

lol
great
what about the oval bore situation.
is this likely or not?
engine was rebuilt within 5k and new rings etc fitted so would rather not do all again
 
<tuffty/> said:
oval bore is plausible yes... have seen a few

<tuffty/>
Click to expand...

Ok thanks
so how do I check if they are oval.
is it in that link?
and also if they are oval where can I buy oval pistons?
 
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daz-20vt said:
Ok thanks
so how do I check if they are oval.
is it in that link?
and also if they are oval where can I buy oval pistons?
Click to expand...

1) with a hammer...
2) yes although it doesn't cover using a hammer
3) Just sand the sides off your existing pistons

<tuffty/>
 
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daz-20vt said:
Ok thanks
so how do I check if they are oval.
is it in that link?
and also if they are oval where can I buy oval pistons?
Click to expand...

with a measuring stick :p
measuring-content.jpg
 
The only way to tell is to measure, measure, compare and measure again... Then go back and measure everything else

If your bores are ****** then the only real option is to bore out and use an over sized piston.

An easier way to check bore health is to get a new piston ring and measure the ring gap at the top, middle and bottom of each bore. Use a piston to push the ring down so you know it's sat evenly in the bore.... If ring gap is within tolerance (0.8mm IIRC) throughout then it should be fine
 
right I was on the wind up and now I've no idea if either of you are being serious
 
OK thanks!!!!
so if they are oval will it be throughout the whole bore?
or can the top be fine and bottom be oval?

is it a piston out job or can I do it while the heads off if I buy a single piston ring and a spare piston? I can manually put the pistons at tdc and bdc
 
daz-20vt said:
OK thanks!!!!
so if they are oval will it be throughout the whole bore?
or can the top be fine and bottom be oval?
Click to expand...

This is much the same as having a puncture where its only flat at the bottom :)

daz-20vt said:
...is it a piston out job or can I do it while the heads off if I buy a single piston ring and a spare piston? I can manually put the pistons at tdc and bdc
Click to expand...

Oval bores = rebore and new pistons if you want to eliminate blow by

<tuffty/>
 
VAG-Slag said:
An easier way to check bore health is to get a new piston ring and measure the ring gap at the top, middle and bottom of each bore. Use a piston to push the ring down so you know it's sat evenly in the bore.... If ring gap is within tolerance (0.8mm IIRC) throughout then it should be fine
Click to expand...

this wont tell you ovality however
 
can I do it without removing the pistons?

so measure in multiple places and rotations?

and do the piston ring measure.
for overall condition.

am I right so far?
 
Sorry dude... checking ring gaps and measuring bores really requires pistons out...

In all honesty once the heads off (as yes it needs to be removed for this) then its not much more work to pull the pistons/rods to facilitate this...

Can be done without taking the engine out but obvs the engine will need to be removed for remedial work

<tuffty/>
 
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Pistons have to come out to do a proper measurement.

Yes, both in parallel to the crank ("A" on the picture) and perpendicular to the crank ("B" on the picture). Measurement should be taken near the top of the bore (approx. 10-15mm down from the headgasket surface). Another measurement in the halfway down the bore. Lastly approx. 10-15mm from the bottom of the bore.

All measurements wrote down from which ovality/conicity/wear can be established.

Using a piston ring is only good for determining conicity and bore wear so no good for oval bores. You need an internal micrometer if you want to do the job right.

golf-mk5-11444.png
 
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ahh ok tuffty.
I'm just trying to suss out what I need to do and worst case costs before I do anything hasty.
would it be silly to take the head off and not do this?
 
Head has to come off to get the pistons out
 
I know mate. the head is coming off regardless as I have to replace the head gasket.
but do I leave it there or do these checks?
 
@Lewis583

did you remove one of your posts?
I thought I saw one asking about oil consumption and checking for unusual marks in the bores?

or am I going mad?
 
Yeah, sorry. I'd written one then upon re-reading it sounded like a child had written it so performed a major edit, lol.

Prior to the engine rebuild were you suffering any oil consumption issues or smoking under load? Or was the rebuild done purely as a refresh when chasing power?

Were the bores honed when the new piston rings were fitted and how was the break in procedure carried out?

Either way I'd have a visual inspection of the bores while the head is off for any unusual markings/damage to the bore. Also compare the 2 cylinders that were down on compression to the 2 good cylinder to see if there are any differences, (maybe ring glazing etc)
 
ahh ok lol

well the engine was rebuilt to add forged rods.
it had new rings no idea on the honing. I won't be able to confirm this either sadly.

head was also rebuilt with new seals guide etc at this time. I was suffering oil consumption but it was the old seals and guides as this stopped once the car was back on the road.

I managed 2.5k and the level had no moved at all.

break in period was oil change at 100 and 1k miles

no smoke under load to my knowledge.

also the current mechanic is since all this work.

and finally the reason the head gasket went was due to bad luck with my fans packing up whilst on track.
car over heated.

thanks!!
 
Well the person who built the engine originally should have honed the bores prior to re-fitting the pistons w/ rings so you should be ok there.

That the oil level has not moved in 2.5k miles is a good indication that the bores are not significantly worn

Ok so due to the car overheating the minimum I'd have done to the head would be a light skim along with a pressure test just to rule out any warping of the head and/or cracks.
 
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so would you chance it being ok bottom end?

it's running hybrid at 330bhp on a pro4 manifold so it made ok power to.

the engine builder has done loads of 1.8t rebuilds I don't doubt his work.

but I've been wrong before lol
 
Dude... considering your plans for the car and your concerns I would just rebuild the engine and be done...

<tuffty/>
 
can you do it for me tuffty
I'll pay you in Cadbury creme eggs and um bungo cartons
 
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