Possible head gasket issue

[Tiger Tim]

Wonder have I a head gasket issue. Here's the story. MR2 MK1A is only used for car shows & vintage runs. When I return from a run the engine has pushed out about 2 inches of coolant into the expansion bottle. But when it cools down it only takes back about half an inch of coolant to the engine. Normally I just syphon out the coolant from the bottle the following day & pour back into the filler neck & repeat after every run. Compression is perfect in each cylinder & radiator, thermostat, filler cap & expansion cap have been replaced. Coolant has been bled correctly & idle is perfect & no sound of air in the pipes. I got my mechanic to detect any exhaust gasses in the coolant using his kit & nothing detected. Pressure must be getting into the cooling system. Not sure why the coolant isn't being pulled back into the engine. New cap is .9bar. Did a 60 mile run last Sat in quite hot weather & extra coolant was pushed out to expansion bottle & a little taken back. I found this time that I couldn't return the same amount of coolant to the filler neck so I'm guessing that there must now be some air in the system. I have a mark on the expansion bottle just above half way so I know what my starting point is. Anyone got any ideas?. Might be a head gasket job over the winter.

Thanks,

Tim

[PW@Woodsport]

Sniff tests aren't conclusive on 4a-ge engines, the HG breach can be so fine (usually around number 4 cylinder to water jacket) that it will only blowby exhaust gas under load.

The test i use is to carry out a leakdown test (just apply 50psi to each cylinder at TDC) with the coolant filler cap off, if there are bubbles then it 100% has a HG issue, if there are no bubbles then it passes.

Over the last 20 years this test and only this test has worked for me, hope that helps.

[Tiger Tim]

Thanks Paul, I read about your hollowed out spark plug on another thread. Was hoping it wasnt the HG but probably is. Will test.

Thanks,

T.

[Tiger Tim]

Haven't got around to doing the leakdown test yet. There was a lot of local shown on in my area last weekend & I used the car quite a bit. Did over 400 miles & no overheating issues. These are just my observations. I know the headgasket is probably gone but will keep doing this until I can afford to do it (or get around to doing the leakdown test firstly) .

As I mentioned previously when the engine cools down it doesn't take back in the coolant it sent out to the expansion bottle. I found that there is air each time in the rad after a run so I've being opening the filler cap then going to the rad & opening the tap on the rad very slowly until I hear the hiss of air escaping. Once air is expelled & I see coolant I close the tap & then I am able to syphon the coolant that has been expelled from the expansion bottle & back into the cooling system.

Will keep me on the road for a while,

Tim

[Tiger Tim]

Hi All,

Sick of watching the temp gauge & syphoning coolant from expansion bottle back into the system. As winter approaches I'll be putting the car off the road & will get the head gasket done. Getting a list together of parts I need. Anyone have a list?.

Head Gasket
Exhaust & intake manifold gaskets
Timing belt & water pump
Head bolts
Gasket where manifold joins exhaust?.
Anything else?.

Must check the BGB.

T.

[jimzzr]

Camshaft oil seals (and maybe do the one on the crank as well)
Timing belt tensioner
Various cam cover/bolt seals.

You'll also need a slim 12 point 10mm (I think) socket for the head bolts if you haven't got one. Maybe a tap to clean up threads

New oring for distributor (maybe do the internal seals if it's leaking)

Alternator belt?