How to / DIY > Engines

ST1 cylinder head gasket

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ajaffa1:
Hi Guys, some of you will have seen that I purchased a small dumper truck. It has a Lister ST1 diesel engine, it is an absolute prick of a thing to hand start (no electric start).

My first thoughts on this was that the injector was dirty. Stripped it and cleaned it, I get a good spray pattern from it. Still a prick to start.

My second thought was lack of compression, so I took the head off it, followed by the cylinder and piston. The cylinder bore is OK, it has a couple of water marks in it where it has been sat idle for a time. The piston and rings look to be almost new, they are original Lister parts but have the numbers 040 stamped into the bottom of the piston. I believe that this indicates a +.040" oversize piston indicating that this unit has had a re-bore. There are also a lot of other indications that someone has been into this engine before me, silicon sealer rather than proper gaskets and etc.

Cylinder head looks to be OK, slight pitting in the valve/seats, I will lap them in the morning.

The cylinder and piston are now cleaned and reinstalled.

My question is a simple one: tomorrow I would like to fit the cylinder head and set the bump clearance. The problem I have is that these generally have a set of shims and a gasket between the cylinder and cylinder head. I have only one steel shim and no gasket. I am happy to make my own shims but I do not remember what the gasket should be made from. Is it paper, or some other material? How thick should it be? could I use a gasket sealer as an alternative? I could order a set of gaskets from the UK but delivery from the UK could take weeks.

Help/advice please,

Bob

cobbadog:
Hi ajaffa1,
Did you happen to check the ring gap while you had it apart? This could be an issue if it is too wide, everything else is good but the gap too wide is not.
As for the head gasket, what type of head gasket came off?

Where abouts on the earth are you as there is bound to be a supplier of Lister parts near you or at least in the same country.

ajaffa1:
Hi Cobbadog, I`m still in Nymboida, NSW, Oz. Nearest town in a straight line would be Coffs harbour, nearest town by road is Grafton. I did phone the nearest Lister agent, they had no gasket set in stock and could not give me a realistic estimate as to how long it might take to get one.

I wish I had checked the ring gap but I was in a hurry to get this thing running. Hope that won`t come back to bite me in the arse! That said the problem wasn`t lack of compression, it was too much compression. I am no longer a young man but would have struggled to pull this one past compression when I was! Crank as fast as you can and drop the de-compressor lever and the thing nearly stops dead.

Some muppet with no idea of what they were doing has been inside this machine! Once I had lapped the valves and reassembled the cylinder head, I fitted it back as it was and did a bump clearance test. It came back at 23 thou clearance, it should be 35 to 38 thou, no wonder I nearly broke my wrist!

It has been a long time since I rebuilt my ST2 startomatic but I remember the bump clearance was adjusted with a stack of circular steel shims with a circular copper gasket at the top. I did not have copper of the right thickness to make a replacement so I opted for annealed aluminium. I think this should be OK as it is tight up against the aluminium cylinder head with steel shims sandwiched between it and the steel cylinder. I redid the bump clearance test and came in at 34 thou. This is still slightly under the specifications but with a little gasket sealer and the 40 thou re-bore should be close enough.

On assembly I found both of the valve push rods were bent! I do wish people who don`t know what they are doing would leave machinery alone.  Push rods straightened, valve lash set and she turns over sweet as. A very slight compression hiss from somewhere, could be rings or valves but nothing to worry about.

My biggest worry is that the same idiot who got everything so wrong may have played with the injector pump timing. On single cylinder ST engines the timing marks on the flywheel line up with marks on the flywheel housing and can not be viewed from outside. Since this engine is close coupled to a clutch, gearbox and transmission accessing the timing marks would be a big pain in the arse! Lets just see what happens tomorrow.

I`ll let you all know how it goes,

Bob

cobbadog:
Well done Bob. I have never been to your neck of the woods only along the coast road many times and will be hitting Coffs again soon.
I thought of Listeroids at Nambucca or is it Mackville somewhere.
Not sure of where the compression leak would be comming from. Did you use any spray sealant on the head gaskets? Or maybe a valve adjustment. Anyway hope it all goes well tomorrow

mike90045:
I think the cyl base shims are just thin paper, you put a stack on, and torque, test, loosen and tear a sheet out, until it's right

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