Just this one quick question, wanted to keep it from my original thread to cut to the chase..

Situation is, my car was showing signs of HG failure for a good 10k miles since I bought it. The thermostat had been removed by the previous owner (dealer) to keep the car from overheating.

Steam was pouring out the exhaust when the engine was warmed-up and did so as long as I would drive it. I was visibly losing coolant and after a while of it worsening, my oil level would rise without explanation.

All these being signs of a HG failure, I proceeded to remove the head. I found the old gasket had been fitted with some kind of sealant (?) but there were no signs of breakages or gaps in the gasket to indicate where it could be leaking anywhere.

Is it possible for the gasket to 'fail to seal' without actually physically breaking? Like become slightly deformed / twisted between the head and block after overheating? I can't figure out how else there is a leak, unless there is a warp between the surfaces or something? Can pitting of the edges of water jackets etc cause leakage into the cylinder?

I am yet to try the engine out since replacing the gasket myself, so have my fingers crossed. Would just like to know some kind of explanation, if anyone can offer one?

Any thoughts and ideas are welcome, anyone experienced this before?

Cheers, Chris

the pitting i've seen in your pictures wont cause a gasket to fail to seal properly, your block and head look fairly good to me.

also it looks like your head has been skimmed before... did you check carefully for cracks inbtween the valve seats?

yes i had a good look all over for cracks anywhere

just to be clear, the 'valve seats' are where the 'trumpet' bit of the valve sits in the actual head, when closed? piston side of the valves, as opposed to the cam side?

if so, yeh i'm pretty sure there were no cracks that side. would that have caused burning of coolant, or gasket leakage somehow?

how do you think the car was burning coolant last time? with the gasket intact?

has me baffled lol

yes that is the valve seats, piston side, made of hardened steel..

the water jackets pass very close to the valve seats to aid cooling, sometimes they crack through, but that normally would pressurize the cooling system rather than make steam..

it' perfectly 'normal' for a gasket to just blow, you can always see where either.. especially if it wasn't sealed/torqued properly... hope you put the new gasket on dry without any sealant too!!

cool, thanks for the reassurance. yeh i put it on dry! hope this works..

ohhh and a slightly unrelated question, i've had the cam off the head as you know.. should i have..

1 - removed the head, then taken cam off the head

refitted cam to head, then head to block

2 - removed cam, then removed head

refitted head to block, then cam to head+block?

was just putting cam on this evening, and cap 3 didn't want to go.. I'm worried i messed something up :S

does it matter which sequence you do these things in, ie - 1 or 2?

supposed to start in the centre and work outwards. the centre cap also acts as a thrust for the cam.

very carefully tighten down each bolt half turn at a time. if you put the cam in the tdc position it should go in easier too (number 4 inlet opening, number 4 xhaust closing), make sure crank is NOT at tdc too. if it feels like it doesn't want to go down dont force it or the camshaft might snap (yes i have done that before on a very rare jap import nissan skyline, i was not popular i can tell you!)...

make sure you have the caps round the right way too, they will only fit one way

also as an aside, if the valves were removed it's prudent to put the cam and make sure it turns before the head goes on the block in case any of the valve springs are jammed ( yes i've done that too!!)

Edited 7 April, 201016 yr by SkodaBoy

lol about snapping the cam worried me slightly there!

i had the crank at 90 BTDC with pistons half way. If it is in this position, can the cam rotate freely whilst not attached to crank without the valves touching the pistons?

also, how hard is the cam supposed to be to turn by hand? it's pretty hard and i can't tell whether it's due to the valve springs as normal, or because something isn't lined up right?

yes 90deg BTDC is fine.

the cam should turn with a moderate amount of force, it will spring round as the valves open and close kind of, not smoothly... if something wasn't lined up right the cam wouldn't turn full stop.

did you fit new hydraulic lifters (tappets) from a breaker?? if so you will need to drain the oil out of them

sweet, its turning fine with that springing motion you described now

just been timing it up and when turning the engine on the crank sprocket it feels just as it did before so i think cam is fine

na i put in a new set of lifters from ECP.. i've had them lying about for about 6 months. haven't put a new cam in yet, not sure how bad the damage is, if there is any (have got pics now in my other thread)

i soaked them upside down in new oil for around 2 days whilst sorting things out

they are now in the engine under the cam, and i haven't started it. i'm going to start it in the morning (few hours time), would that be enough time to let them 'settle'? i'm not exactly sure if i've done it right, as i don't understand this settling process they require lol

will have the exhaust back on it in the morning, fill up the fluids, do all the other pre-flight checks then will give her a whirl!

Hey, up pretty late I see...

Anyway, good luck for the morning!

PoloD.

make double sure you turn the engine over 2 complete revolutions and re-check the timing marks before you kick it in the nuts

Riiight.. think i'll post in here as i get more responses lol

started the bad boy up today.. not so great

it turned over the same amount of times as normal, if a bit sluggish (probs battery)

caught well, but when idling there was a horrendous chirping / screeching coming from somewhere. the engine was also close to cutting out at times, jerking about a bit but not revving highly indicating a vac leak. very tappety

turned it over a few times (3?) and was doing the same thing, but the screeching sound become more intermittent

i checked the cam timing for a slipped belt or something and it was fine.

started it over again and it idled fine, the screeching sound disappeared altogether! but it was still sooooo tappety.

is this normal for a start up after a head removal? I've got some shit old oil in from my mates clio to clear all the crap out after a bit, but i don't think that was causing it

i'm also worried that its very tappety, and worried about that horrific noise coming bcak. any ideas what it could have been?

i'm too scared to rev the car incse it goes bang lol. i'll try and upload the vids and soundclips i got of it, bloody iPhone

cheers

Assuming it's like any other VW OHC - did you set the tappets?

if so you will need to drain the oil out of them

and i even quote myself now....

the lifters should pump up and stop tapping on thier own assuming they were empty to start with

balls, i thought i had but clearly i hadn't (i did see what you wrote dude)

they were *new* lifters so didn't have oil in them

but i soaked them in oil upside for a day or so (was this a bad thing?)

EDIT TO ABOVE - i did this because of the following thread (see 'Charlie's comment). I'm guessing this is totally wrong? - http://www.clubpolo.co.uk/forum/index.php?showtopic=152654)

right, i'm going to take them out tomorrow then.. how exactly do i 'set' them? literally just keep them upright (cam face upwards, as in the engine) and let the oil fall out?

more importantly, how much damage is this likely to have been caused? it's only been ticking over at idle for a collective maximum of 60 seconds..

Edited 8 April, 201016 yr by CWA

I had a similar problem a while back and was speaking to my mate about it. He reckoned it could be just a pin hole in the gasket. Its enough for gasses to flow into the coolant and heat it up which would cause it to over heat but its not big enough to let the oil and water mix. So you get the symptoms but without the obvious mayo in the cap.

I had a similar problem a while back and was speaking to my mate about it. He reckoned it could be just a pin hole in the gasket. Its enough for gasses to flow into the coolant and heat it up which would cause it to over heat but its not big enough to let the oil and water mix. So you get the symptoms but without the obvious mayo in the cap.

ah i see what you mean.. wouldn't that just pressurise the coolant system? as opposed to burning the coolant itself?

could have been that, tbh as long as changing the gasket has sorted the steam and overheating i dont mind :)

so.. I'm draining these tappets by taking them out and leaving them UPRIGHT for X amount of time.. NOT filling them with oil

here's another one.. what happens if the cam caps are too tight? could this have caused a horrific sound?

what damage would be caused?

and what if they are too loose?

had a bad time trying to guess the correct torque for them bearing caps :/

how do i know when tappets are fully drained enough?

could do with some experience on this.. i'm pushgin the valve contact bit and there is still oil coming out a little?

right i drained the tappets of all the oil by pushing the springy bit in and pumping it all out of that hole. as far as i know they were empty when they went in the car.

put the cam back and the belts. started it up again and the same noise occurred, the whirring / chirping / squealing sound.

am pretty worried now, what can this noise be? are the tappets supposed to make a noise like that when they are new in or do they rattle?

has something messed up quite bad?

how would i know if piston-valve contact has occured?

could really do with some help on this chaps, please..

if the tappets are springy that is fine...

ref: squeeling, are you 100% sure you put all the cam caps back on the right way round? also are you getting any oil pressure at the top of the engine?? try briefly starting it up with the rocker cover off, and you should see some oil flowing around the head

you are very unlikely to have suffered piston to valve contact unless the engine was timed up wrong, normally there is plenty of clearance for the valves on these engines

if the tappets are springy that is fine...

ref: squeeling, are you 100% sure you put all the cam caps back on the right way round? also are you getting any oil pressure at the top of the engine?? try briefly starting it up with the rocker cover off, and you should see some oil flowing around the head

you are very unlikely to have suffered piston to valve contact unless the engine was timed up wrong, normally there is plenty of clearance for the valves on these engines

i'm about 90% sure they are right.. there are pointy bits on the exhaust side of the caps, and square bits on the inlet side? the number 3 cap is still blinking hard to get on though. when replacing cam, i put on caps 2 & 4 as haynes manual said and tightened them to the bottoms of their thread (not torqued). then i slotted on nos. 1 & 5 and they sat on the cam journals perfect, but 3 was an awkward bastard and wouldn't slot on. i screwed the nuts down and it kind of 'clamped it' down, but i didn't think it would be that hard?

from what i remember, it was like that both ways round.. although now i'm not sure. i even loosened the cam caps about 30 degs as i thought i may have overtightened it.. didn't do much.

i will try running with the cover off and see what happens. i'm not getting an oil wrning light or buzzer though, so i guess theres pressure by the sensor?

the cam timing is 100% spot on to the tooth.. are you sure i could not have incurred any pitson-valve contact? i was worried about the missing when i first started it.. and another thing i noticed - it hisses a little when i stop the engine.. ?

it's normal for it to run a little rough at first whilst the tappets are adjusting themselves, it's because the the valves are not opening very far to start with until they are pumped up..

it's probably your number 3 cap that is causing the screeching noise then if it was uber tight to get on... you did use the right cap on the head didn't you?? ie, you didn't take the cap from the head you got the cam second hand camshaft from right??

it's normal for it to run a little rough at first whilst the tappets are adjusting themselves, it's because the the valves are not opening very far to start with until they are pumped up..

it's probably your number 3 cap that is causing the screeching noise then if it was uber tight to get on... you did use the right cap on the head didn't you?? ie, you didn't take the cap from the head you got the cam second hand camshaft from right??

na it's definately not that lol, i haven't actually got a second hand camshaft yet!

it's the old cam.. haven't touched any other caps and don't have any others lying around in the garage. when i'm putting the cap 3 on, it almost feels as if the cam journal 3 isn't actually wide enough for the bearing cap to fit onto it.. ? i might just be clutching at straws or something, but i can't think why else it would be so hard to get on. once the nuts are tightened it seems to slign up fine, but must be under alot of stress

i will try turning the cap around tomorow, but if that shows nothing.. do you think the cam is damaged, and is possibly bent or something? or the head has actually warped in the top section, is that possible?

and you are 1000000% sure that this engine can't incur piston - valve contact with the tappets fully filled, pushing the valves down more? it would be so great to rule it out, as earlier this evening the prospect of bent valves was dawning on me..

tbh, without seeing or hearing it, it's all a matter of speculation to try and diagnose and fix a car via the internet.. but i would almost bet that there are no bent valves, there would be no compression otherwise and you wouldm't get the hissing noises when you turned the engine over by hand...

cam's don't bend no, they will snap if you put too much stress on them, the heat treatment process makes them hard, and also brittle!!

it is possible for the cam bearers to become warped, i've never seen it on a vw engine though, i've seen it on the old OHC vauxhall engines when they have cooked up good and hot.

oh and btw the caps should be numbered if you look carefully too, and the numbers should be the right way up if you are stood facing the front of the car

Edited 9 April, 201016 yr by SkodaBoy