Club 80-90 Forums

Today I changed my cracked cylinder head. Not a bad job really. Took the inlet off, pivoted the exhausts away drained the coolant. The head came off lovely, bores stayed where they were. The green seals were still ok as they have only done 2000 miles but I changed them anyway. New head seal rings were fitted and a second hand AMC head with new valves. All in all it took 5 hrs!! I noticed some arcing marks on the spark plug body of cylinder one so have ordered a set of leads. Also shock horror my waterpump is leaking from the packing hole (new 2000 miles ago from GSF, rubbish quality that was!!! ) so I havent filled up the water yet to try her out I'll wait for the new pump and leads from brickwerks. (they were out of stock when I ordered the one from GSF)
Looking at the old head I have found a crack across the narrow metal between where the liner goes and the cylinder bolt drilling, It runs a long way up the inside and runs through to the exhaust port. It is only a hairline crack but obviously enough to let water through as steam. The hairline crack between the valves on cylinder 2 has also worsened to about 1 mm. This head is scrap now but I'll keep the valves and springs.

lpg a coincidence you think?

https://club8090.co.uk/forum/viewtopic.php?f=37&t=118129" onclick="window.open(this.href);return false;

RE: waterpump.
Maybe the cooling system was running at a high pressure due to a combustion chamber to cooling system leak and the excess pressure found the next easiest route out, through the waterpump?

My cracked head didnt noticably pressurise the water system as the crack was from the water to the inlet/outlet side of the valves, the crack did extend to the combustion chamber except just the tiny bit between the valves,
but interesting you say that mr b because i was loosing a little coolant regularly and i did kill a couple of water pumps so well be maybe related

My symptoms were just lots of steam from the exhaust and a rusty spark plug
http://www.brick-yard.co.uk/forum/rusty ... ack#623963" onclick="window.open(this.href);return false;

123-jn was the system pressurised? What were the symptons

My lpg was lean i think and i wonder if this was the cause of the crack or is it just that 198* heads will all eventually crack?

The cooling system was only pressurised in the normal way, crack did not go into the combustion chamber twas between a stud hole and the exhaust valve chamber which caused steam in the exhaust and a pressurised and mayonnaised rocker box!!! Also a very noisy unlubricated exhaust valve. The valve heads were also rusty!!
I reckon it was just a ******* waterpump as there is now also play in the shaft bearings.

123-jn wrote: I reckon it was just a ******* waterpump as there is now also play in the shaft bearings.

if the system was not pressurised cant see the two are related

got any crack porn for us?

cant help wondering about lpg though, not one other responce saying yes i have had that and here we are two lpg vans with cracks between the waterway and exhaust ports

i see you have gone closed loop, i did this because i suspect lean running caused the crack

lots of lpg vans out there, if you are getting good mpg then i think you are running lean, everybody wants good mpg

I am getting between 17 and 20 mpg on gas and around 22 on petrol, The closed loop should keep the mixture correct and that is what the test lights say but the plugs dont go the same colour as when on petrol. They run a very light brown close to the white of the insulators, no black on them at all. The crack was in all possibility caused by the separation of the head from the liner with a little too much mallet!!! This invisible weakness then spread though the head bolt drilling as far as the exhaust port and opened up into a crack as the engine was run in. (that's the verdict of the machine shop who say it is now scrap) . Mine only ever did about 600 miles on open loop and that was before the engine rebuild so I dont reckon it was the gas, it was my poor machanics skills more likely!!!

Doh

Just tried to take pics of crack but my camera is not up to it They just dont come out on the picture even though I can see them with my bare eyes. I tried with and without flash. I will try again in natural light at the weekend, they are very hairline but steam seems to get through!!!

Sorry chaps I cant get the cracks in the head to show up on a photo!! On a positive note the right side of the engine is now super quiet with the AMC head, hardly a tap or a rattle to hear unfortunately the left side is still rattly, reckon it might be down to the valve guides which were approaching maximum allowable sideways movement of the valves. One day I'll change that side too!!! For now it is summer!!

Have you tried cleaning the cracked area with emery often helps as crack holds the dirt

If not how about drawing where the crack is with a marker Interesting to see