Head gasket gone i think but no oil/water mixing.

[hackett]

Hi guys a mate of mine has a bloody mg zr 1.4. As i told him it would i think the HG has failed. He was driving along and said the car over heated. He stopped thought nothing of it and then continued to drive for 8 miles

He said for the last few weeks there was no heat coming out of vents so i said i would have a look at it. Well it won't start for one and i did a compression test on it. I got 105psi on cylinders 1 and 4 and 40 psi on 2 and 3 (if 1 is the far left cylinder then 2 then 3 then 4.

This looks to me like its proper cooked and has warped the head. The only thing is theres no water mix or oil mix. When i undid the rad top hose there was no water in it at all even though the expansion tank is at correct level. I think there is a blockage in the cooling system which has then caused the over heat and then the blown head gasket.

Does this seem plausable or have i completely missed something. The heads coming off tomorrow. Its just becausr=e the water and oil hasn't mixed i don't want to waste my time if its not the HG. What does everyone think??

Thanks

[MrFlibbles]

When the HG went on my MR2 Turbo there was no oil/water mixing.

[Boosted LS1]

Water mixes with oil if there are adjacent passages. The gasket may be shagged and coolant may have gone down the exhaust port instead of into an oilway.

[hackett]

so do you think with the results of the compression test it will be the HG then??

[Boosted LS1]

Could be, but it could also be coincidental, ie a fault in 2 adjacent cylinders. Either way. I'd start by lifting the head after checking the valvetrain hasn't been damaged in some way. I think you're on the right track.

[Steve_D]

hackett said:

........Does this seem plausible or have i completely missed something. The heads coming off tomorrow. Its just because the water and oil hasn't mixed i don't want to waste my time if its not the HG. What does everyone think??

Thanks

Makes little difference at the moment with those readings for 1 & 2 the head has to come off. It is quite possible for the head to blow either between cylinders loosing no fluids at all or blowing into the water jacket and not contaminating the oil. You tend to get oil showing in the water when the blow is progressive so some oil and combustion products start to show in the water.

I feel your friends pain but the ghoul's on here (myself included) will need to see photos of the carnage revealed tomorrow.

Steve

[hackett]

Hi fellas thanks for replies.

Don't get me wrong i'm quite a confident/competant mechanic i've rebuilt a few engines so this is a pretty easy one but i keep finding myself going out with my breaker bar and socket to whip the head off then turning round thinking "but what if the heads fine" even though the compression results are shocking which does show a mega issue.

Well inlet and outlet manifolds are off and tomorrow i will whip the belt off and the head and hopefully see some scorches across the HG.

Ta for replies if i get chance i'll stick some photos up of the block/head.

Although if the sun is shining i'll be out on my bike so the car can wait lol.

[stevieturbo]

Its a Rover K-series....its a pretty safe bet its blown a head gasket....

[That Daddy]

stevieturbo said:

Its a Rover K-series....its a pretty safe bet its blown a head gasket....

Oh yes i hope its not been cooked i have seen these motors with the top part of the liner come off in your hands along with melted ring lands,they dont tolerate overheating especially being boiled dry,but then again why should they,i have done many headgasket replacments on the K and have had none come back(you have to check everything is A1) i also educate the owners after not to ignore early signs of water loss or oil in the radiator expansion bottle.

Edited by That Daddy on Sunday 16th November 19:13

[OJ]

stevieturbo said:

Its a Rover K-series....its a pretty safe bet its blown a head gasket....

More precisely, as its a K-Series that has overheated, it will definitely be a head gasket. If the cooling system is working properly the head gasket is not as much of a problem as people make out.

Make sure the cooling system is checked if your mate intends to repair/replace the head, otherwise he'll get a few months down the line and it may well go again.

Typically its silly things like expansion tank caps and O-ring leaks that cause issues

Edited by OJ on Monday 17th November 11:31

[Marf]

MrFlibbles said:

When the HG went on my MR2 Turbo there was no oil/water mixing.

Ditto on my Charade GTxx, the blow was about a millimetre wide between cylinder 1 and a waterway. It was using a little bit of water and bubbling a little in the expansion tank. Had I not been paranoid about listening for bubbling after shutdown and checking water levels every couple of weeks I wouldnt have spotted it.

Sniffer test confirmed combustion gas in the coolant system.

Edited by Marf on Monday 17th November 11:53

[hackett]

Quick update for you. Took the head off and low and behold the fire rings from the HG had left a nice deep indentation in the head it was also very visibly warped. Checked with an engineers rule it was clear that the head was fubar.

Well the guy is on his honeymoon now and when he gets back he is going to source a new engine as i told him i wouldn't feel comfortable fitting a new head to the block as the chances are the block will be screwed as well.

Cheers for replies folks

[FWDRacer]

Depends on what you decide to do but I've got a K-head that has just been rebuilt and lightly skimmed, more as an insurance policy more than anything.

Brothers 216 Cambelt let go, so we purchased another head. The original one was rebuilt, he got away with 4 bent exhaust valves only the lucky Bstad .

http://www.pistonheads.com/gassing/topic.asp?h=0&a...

Hence this one is up for grabs inc cams and cam carrier/pulleys.

Located in West Mids. PM me if you or your mate are interested and I'll let you know all the details/casting no. etc...

Edited by FWDRacer on Wednesday 19th November 11:45