Hgf?

[Sean]

The past month or two, my car sometimes seems to want to overheat when it shouldn't, and hadn't before in similar (and worse) conditions. Expansion tank level seems to change a bit, but sporadically. I'm thinking this is likely to be head gasket failure, probably related to the thrown belt overheat I had in the summer, and possibly magnified by a day of flogging it around the track a couple weeks ago.
This brings up a couple of Qs:

1. How to definitively tell if this is HGF?
2. If not, what else might cause this behavior?
3. Any tips on what to do/avoid doing when changing a head gasket?

Any pointers greatly appreciated, as I've only changed a HG once before, and it was a good few years back.


edit -- Oh yeah, my speedo quit working on Friday as well. That one should be easy enough.

[moosetestbestanden]

1. How to definitively tell if this is HGF?

Compression test? (I had a similar incident w/ Crusty, which ended up causing HGF & a cracked cylinder head)
I believe a time-worn test is to look for water in the oil too. Or is it oil in the water. Anyway, you get the idea.

2. If not, what else might cause this behavior?
3. Any tips on what to do/avoid doing when changing a head gasket?

Any pointers greatly appreciated, as I've only changed a HG once before, and it was a good few years back.

I'm sure Magnus can help here and I'm sure he'll be along directly.

Oh yeah, my speedo quit working on Friday as well. That one should be easy enough.

Yeah, well, that's what I thought too. I have yet to find the source of my problem. I've changed EVERYTHING, except the instrument.

[Doug Liedblad]

Remove radiator cap and run car. Sometimes you can see bubbles in the coolant.

Remove spark plugs. If water is getting into a cylinder it will be very clean.

Is excess water in the form of steam coming out the exhaust? After it's at temperature as there is always water in exhaust but this would be excessive. If you run antifreeze you can smell it.

If oil is getting an off white foam that means water is getting into the OIL. Usually this is head gasket failure. Don't run the engine too long if you see this.

Compression test or leakdown test. Leakdown requires an air compressor or at least a source of compressed air or nitrogen. The leakdown tool which can be had from Harbor Freight cheap.

[magnusfeuer]

Doug pretty much nailed it.

Water contaminated oil is usually a lighter brown shade and likes to gunk up in the oil cap, etc.

/Magnus F.

[Sean]

No cream-colored foam in oil, no steam or A-F smell from exhaust, and no visible bubbles in coolant (although, no radiator cap on radiator - just a bolt - but no visible bubbles in expansion tank). I'll look into the cylinders and do a compression check in a few days, I hope.

Thanks for the quick and straightforward replies.

[Doug Liedblad]

Sean

If you have a Raceline water rail with a filler cap you can check there. Remove it cold and start it with coolant over the thermostat. I am not convinced this is a reliable test but have seen it work on occassion.

Usually pulling the plugs tells you as much or more.

[magnusfeuer]

Good summary of overheating causes:

http://voices.yahoo.com/8-things-cause-car-overheat-7520442.html

[Doug Liedblad]

Yes, it is good summary and note that the HGF is listed last.

I'd check for trapped air as the Zetec was reported to have an issue with it. I don't know about the Duratec.

I raise the front of my car up so the bolt in the top of my radiator is the highest point in the cooling system when filling from empty. Or at least as close to the highest point as practical.

I would have mentioned all of that stuff but figured you knew it already.

[racemachine_sweden]

Hello Sean,
I am a newbie on this forum that live not too far from you (La Honda).
A rather unusual type of water pump failure that sometimes happen to certain types of pumps and can be tricky to diagnose is when the impeller comes loose from the axle or the impeller corrodes to such a degree that the pump gradually looses its pumping performance.
Best regards,
Andreas

[moosetestbestanden]

I know all about how to install an electric water pump on a Duratec engined Caterham you know, right down to which pin in the ECU. :-)