Blown head gasket?

[RRHANS]

This morning temp shot up.
Checked coolant and it was dramatically low.
filled her up and 50km on, temp went up again, coolant gone again.
I let her cool down completely and filled her up again and let her idle to operating temp.

There was no pressure build up in the cooling system during warmup and there were no leaks.
There is no water in the oil and after warm up and coolant in expansion tank is cloudy white without oily deposits.

So my guess is intake manifold gasket if I am lucky and head gasket if i am unlucky.

[Lotus-e-Clan]

Check compressions with all plugs out ... also see if you get any water ejected from the plug holes.

Do the tail pipes steam more than usual during warm-up?

Check the header tank pressure cap is working properly in case water is lost via overflow...it should pressurise quite well..if it's not then maybe some water is lost via expansion each time.

I did a pressure test on my cooling system during the conversion process to Evans waterless coolant and you could try it yourself...

• 1) Drain the cooling system
  2) insert a T piece into the heater take off from cylinder head (or anywhere convenient) to enable you to insert the valve from a 12v tyre inflator to pressurize the system
  4) You should be able to get the system pressurized to 10 -11 psi before the cap opens and lets the air out.
  5) listen for air leaks (with plugs out) - it you have a leak it'll be pretty obvious by the location of the hisssssss!

I thought I had a problem with water loss before I took out the engine for a clutch change. I found the cylinder head bolts were unevenly torqued so I re-tourqued by 'cycle-torqing' each head bolt x3 and I've had no issues since. It's more important that head bolts are EVENLY torqued than the absolute torque value (within reason).

[AndyC]

This morning temp shot up.
.....So my guess is intake manifold gasket if I am lucky and head gasket if i am unlucky.

I doubt inlet manifold, as I cannot think of anywhere that it has oil passing through it, so it wouldn't explain the oil in the coolant tank.

[RRHANS]

There is no oil in the coolant tank.
Started her up this morning to investigate.
Started immediately without any hick-ups, replaced coolant tank cap with the one of my TR6 (same size).
I found some coolant in the cavities under the distributor but did not see any dripping during warm-up.
System still did not pressurize.

I will pull the plugs and investigate further.

[AndyLotus]

One test I did to prove that my head gasket had gone was to pressurise the combustion chamber with compressed air.
Ensure the valves are shut for each cylinder you test, stop the engine turning over with a large screwdriver jammed in the ring gear via the hole under the starter and stick 80PSi or so in via the plug hole. Listen for escaping air.

In my case pressurising cylinder 4 led to the air escaping via the carb mouth of cylinder 3. The gasket had blown between cylinders 3 & 4.

[CHRISYD]

check the rubber hoses between the inlet manifold and the heater matrix areas. also, if the engine is sucking water into a cylinder or two, the plugs will be cleaner than others.

[RRHANS]

Great idea's

Will pull the plugs this evening, check colour of plugs and piston heads for "steam cleaning".
Next compression test.

Is there a easy way to connect compressed air to plughole?

[AndyLotus]

To connect compressed air to the plug hole I used part of a compression tester adaptor. (ie that fits the spark plug thread and seals)
This was then bodged together with a standard air 'blow gun'. I seem to remember a fair bit of messing about with threads and PTFE tape to get it all to seal.

[CHRISYD]

i seem to remember a blow gun with a rubber adapter on the end for similar jobs (or was it a compression tester with a rubber end that you pushed onto the plug hole)

[garyexcel]

Just a thought a while ago I had a problem with lost coolant at speed it turned out to be a tiny hole in the pipe between the thermostat and the inlet manifold difficult to find because it was at the bottom. found it by pressurising the system with air.

Gary

[RRHANS]

First test results in the "boiler room".

Pulled the plugs, all looked afternoon tea (with milk).

Flashlight test.
All piston tops looked sooty except for number 2 which looked fresh aluminium.

So number 2 definitely steam cleaned.
Coolant on block cavities under dissy corresponds with number 2.
Still hope it is inlet manifold gasket.
It is a bit soon to have a head gasket since the rebuild 2 years 10000km ago.

Will pressure test this weekend as you all suggest.