What reading should I get...

[Hurricane]

From a compression test? I have a storm I've been working on for a few years and now I'm tackling the engine which is overheating, so what's the max/min reading i should be getting? I'm new to this but have learnt a lot from this website already. Should see you all soon at a show I hope

[mark1gls]

Hello and welcome,
I think the haynes manual does tell you what it should be, can't remember without looking but I think had approx 160psi when I did mine last on a 220,000 mile DX engine.
The thing to look out for is alot of difference between cylinders.
I have one of these testers.

http://www.amazon.co.uk/Gunson-G4101-Hi ... B002XERM66

I think between 150 - 200 psi is about normal?

[Hurricane]

my mechanic has just got in touch with me and told me that 3 cylinders are reading at 150psi and the 4th is at 160psi which he thought was too little difference for it to prove that it may be a warped head and justify skimming it. I'm a somewhat frustrated as I thought that I'd discovered the problem. For those interested, the engine overheats in about 5 mins while sat idleing! Hoses are good, most replaced with silicone, thermostat has been removed, electrics have been sorted, water pumps good. I'll do a sniff test to check for exhaust fumes to double check I guess. Have I missed something obvious?

[ianaudia4]

Does the fan work?

[Hurricane]

The fan kicks in around midway on the temp guage. No problems there

[ianaudia4]

So when it is sat idling the gauge is in the red and the red light flashing?

[Hurricane]

It will work its way up from cold but I've never pushed it right into the red, the engine starts to really kick the heat out and with no airflow except for the fan really going for it, I worry about causing extra damage. What I'm getting at is that I'm pretty sure the sensor is fine as I've never known an engine to get so hot so quick and that's not using the guage but standing in front of it.

[mark1gls]

Is there an air lock in the cooling system? Take the expansion tank cap off and run the engine, (you do not need to run the engine for very long) there should be water running in from the thin hose going from the top of the radiator, when you rev the engine the water flow should increase.
Also is the heater in the car blowing hot air?

[Nate]

sounds like the coolant isnt circulating properly. likely causes (assuming the pump is good like you say) is that the system is blocked either with sludge or an air lock. sludge can cause big problems, particularly common if the coolant hasn't ever been changed, or it's been run with just water in, or the wrong type of coolant has been used (and yes, i know there are people on here using the wrong coolant who have yet to have a problem, but i'll be here ready to laugh when they do)

has the cooling system been flushed out with a hose? has it been cleaned with a de-sludging agent (you can buy a chemical to do it, or use a couple of caps of biological washing liquid. just pour it in the expansion tank, run engine for a while then flush both directions with a hose) i would be tempted to clean and/or flush it then refil it with water and test it, then when running correctly, redrain and fill with the correct coolant mix

what sort of condition is the radiator in? are any of the rubber hoses badly cracking, particularly the smaller ones? (they can collapse inside)