Cracked Head??

[CwazyWabbit]

If the valves are getting too close to the pistons after a head skim then you recut the valve seats to put deeper into the head, if you skim a block that is when you would increase the head gasket thickness.

[JB750]

Managed to get the head skimmed today. The guy said he took around 3 thou off (approx 0.076mm). Not too bad apparently. So at least I now Know it's flat again

Just got to wait for my gaskets etc. to come so I can get the damn thing back together and hopefully on the road!!

At least it's given me an excuse to get everything cleaned up in the engine bay, there was a fair bit of oil flying around over time from odd little weeps and it's amazing how much it soon covers the whole bay!

[Boydie]

Obviously JB you are going to spend a couple of tiresome hours lapping in the valves ( a task I hate ) but its well worth the effort, whenever I do this I test the seal with kerosene, with the 300Tdi not having a combustion chamber purchase 4 PVC drain pipe sockets, 75mm (I think) and using contact adhesive glue them to the head and fill them with kerosene, the next morning you will see if your valve lapping is good. The contact adhesive can be easily removed with acetate.

I'll almost guarantee that the oil leaks are from the vacuum pump and fuel pump seals, when re-fitting use high temperature joint compound, torque the bolts up correctly and you shouldn't have any more problems. The other oil leak you may have is the small welsh plug on the vacuum pump, if this is the case then a new pump is the only real solution, I have seen threads here regarding repair of the main end gasket by drilling out the pop rivets and replacing them with nuts and bolts but in reality oil should never get into the end of the piston, it does so due to the shoddy design of the Wabco Vacuum Pump, I tossed mine blanked off the camshaft port and replaced it with an electric unit - quieter engine, higher vacuum and zero oil leaks.

[JB750]

Yes Iain, you're right, did the lapping in last night. I saw a great video online from the US where the guy was doing the same and had a quick way of testing for a seal in the valves. Simply fill the valve cavity with a solution of water and washing-up liquid (same idea as for finding a leak in a tyre) and then use an airline to blow air in through the port. I did the lapping the normal way and checked for the continuous grey line all around the valves and seats (old skool way ) then tried the airline trick. Found 3 of the four inlets blew a lovely stream of bubbles, so I re-lapped those valves and now all are sealed.

I'm not sure if it is going to show leaks the way that your method does, but I think it will be pretty close.

With regards to the oil leaks, I replaced the lift pump recently and used gasket and compound to seal it, but I also suspected the vacuum pump so removed that and ordered a new gasket for it. By welsh plugs, I noticed 2 plugs that look like core plugs on the front of the pump, I guess this is what you mean? If so, I don't think they are leaking as the body of the pump seems reasonably clean. You also mention that the your engine is quieter when you replaced the pump, I have noticed a sound from the engine area (a little like a mechanical ticking/whirring noise) which you can hear from inside the cockpit more as there are less 'diesel noises' than when listening under the hood. I wondered if that may possibly be the culprit?

As as a matter of 'just in case', do you have any more information on fitting an electric pump as this may be a future project?

Thanks again for all your good info mate

JB

[JB750]

Finally got everything back together, engine started up pretty quickly and ran sweet. I let her run until the temp stabilised and it seemed steady and no signs of any water leaks so far. I will check her again in the morning and then try a short run to get the thermostat fully open so I can check the radiator and top hose for leaks. I did find out while searching the forum that there is a core plug behind the water pump and mounting which I didn't know about! I am not sure whether to try and replace it in-situ as I have replaced all the other core plugs as a matter of course while I had the engine out.

Only thing is..........damn vacuum pump is leaking oil!! I'm going to do the repair that has been posted on the forum as the brakes seem fine, but I'm sure it is only a matter of time before the pump gives up the ghost. I am now after information on fitting an electric one (any recommended types?) and blanking off the block where the mechanical one fits. Any info would be gratefully received.

Cheers

[Boydie]

Hi, JB I got my electric vacuum pump from EBay,

Its about 8cm wide x 10cm long x 8cm high and machined from a single billet of alloy, basically its a 12 volt motor with a crank that operates a rubber diaphragm with two poppet valves, - inlet and outlet, it raises sufficient vacuum for me to stop after the engine has been run for around 30 seconds, once it's design vacuum has been achieved it turns off meaning that on long roads it is off, coming on only when the brakes are used..

It was supplied by OZ Drag, a "local" drag car parts suppliers. It came with vibration mounts and a built-in vacuum switch, there is/was sufficient room to fit it on the wheel arch next to the brake power assist unit, wiring is 4 amps meaning that you can hook it into the FIP fuel valve supply. Pipe connection was a 1cm id vacuum hose pressed onto the connection of the pump and to the power assist unit - about 25cm long. I ran the exhaust hose from the pump to a nipple which I'd tapped into the blanking plate (original vacuum pump location).