abf ecu changed, now head gaskets blown! compression results in #fresh results in#

test done at 80'c oil temp.

1- 12 bar 175psi
2- 12 bar 175psi
3- 12 bar 175psi
4- 12 bar 175psi

exactly the same on each cylinder. i suppose the rings are ok then. but surely if the sniff test came back positive, one cylinder would be slightly down?

 

haha pretty much what we thought. its still alive, i bet the engine place were telling porkies.

how does it drive now anyway?

 

82, didn't neils mk2 do the same thing? on the way back from lakeside one night?

 

im a c0ck. those results were with the throttle closed! i bet they would be higher with it open! still, looking good!

drives like a dog, then clears up.. no coolant loss, and its the same colour. occassionally misses and looses power, then picks up again. its weird as sniff test came up positive, once the stat had oponed.

 

there was a kink in the ecu vac pipe as well, trapped in the f00king bonnet hinge. shall i drive it round for a while and make sure temps dont get too high. oil below 90? surely if i keep my eye on it, as well as water temps, as long as it doesnt overhaet no damage will be done?

 

muppet... throttle OPEN

vac pipe CANNOT be kinked. that has to be tip top

Neil's mk2 abf (on kjet) did blast out a ton of smoke one night (trying to match my mk3 haha) his was simply over filled with oil.

oil temp on this engine is safe to over 120* but water temp should never go over 90* really.

normal oil temp (dependant on the oil grade etc) would be about 90-94*

 

will the throttle closed falsify the results? or just give an overall lower reading.
blew through the vac pipe and it wasnt as free flowing as i thought, so old one put back on.
oil level was max, but not over.

 

it would be limiting the amount of air getting in etc so it wont be accurate. for piece of mind id do it again

 

I expect the readings will be lower if you did the test with the throttle shut. Muppet
At least they are all the same though.
Is it losing coolant?
Does it misfire a little when you start it first thing in the morning?

 

im on it again in the morning. if the readings go up from 175psi, its looking like a healthy bottom end!

no coolant lost or mixed with oil! it had a poor idle, and nearly clears when warm. loosing power. misses under load though. cant really see any water in the oil

Mr_Hillclimber suggested maybe the ecu is buggered. maybe advancing too much, pinking, and blew the gasket.

it only smoked on start up. although i didnt put it under too much load.

 

new results in- opened the throttle this time

1- 12.9 bar
2- 12.8 bar
3- 12.0 bar
4- 12.9 bar

so it looks like no.3 is down a bar from the others. are we thinking this is where its leaking into the water jacket?

drove it today. no overheating, not smoking too much, only on start up. definate loss of power. wont really pull in 5th at all

 

12.9BAR - 187.1 PSI
12.8BAR - 187.0 PSI
12.0BAR - 174.0 PSI
12.9BAR - 187.1 PSI

7% DOWN

when you swapped the engine, did you do the cambelt at all?

 

Over filled mine a few weeks ago by being a muppet. Blew soooo much smoke...

Ian...

 

new vw belt and auto tensioner were fitted

 

Was this second compression test also done with warm engine?

If so, I'd be tempted to repeat it when cold, that way, if you do have a slight leak past a firering, you may find that the cylinder that was down on compression hot, is up a bit relative to the others cold. This would indicate that some coolant is getting into that pot, and reducing the volume, so will show a higher compression reading.

Leaving it to go cold allows the residual pressure in the cooling system to squirt anything it is going to squirt, into any cylinder it can.

 

yes it was done hot. il try in the moring when the blocks cold.
im not sure if it makes a difference, but the expansion tank(mk4 item with matching cap) was hissing when i was doing the comp test. no bubbles though

 

Was the cap on or off? If the cap was on you shouldn't hear any hissing as this would indicate escaping air or a pressure build up.

 

the cap was on

 

new compression results in-

cy\b cold warm
1 12 12.9
2 12.1 12.8
3 10.5 12
4 12 12.9

so cylinder 3 is 1.5 bar down cold, .8 bar down warm. well witin spec. do we think this is where the gasket has gone into the water jacket? as the sniff test was positve for combustion gas in the coolant.

 

Trouble with the sniff test is that if you've ever had an oil-cooler failure, remnants of oil in the cooling system may confuse matters chemically.

I wouldn't rush into blaming the HG, especially as you said you're not losing any noticeable amount of coolant. It could be a dodgy piston ring causing pressure loss, or a valve that isn't seating right.

I'd whip the sparkplugs out, shine a torch down into the cylinders, and look for any damp piston-crowns. If you do see any fluid, sample it with some kitchen towel on a stick, and examine it by smell and colour.