Overheating

[hachi-roku]

I took my car out today for a spirited run and all seemed fine, enjoying the scenary etc, however on the way back I was keeping an eye on the temp guage and all seemed normal and was positioned at half way, I looked at it about 10 seconds later to see that it was nearly in the red so I pulled over and let it cool down for about 15mins, I noticed there was a bubbling noise from the expansion tank. I drove off again taking it nice and easy the revs didn't go above 4k on the way back and I stopped off to get myself some food (too lazy to cook and an indian sounded nice), but as I parked up the temp was again near the red and I had been watching it like a hawk so it had only just bumped up.

I had recently had problems with air in the coolant and I was sure I had got it as it hasn't done any funny idling or anything, the car isn't smoking and there is no mayo in the oil so it was suggested that I have an air lock somewhere.

Could it just be air, or still very possible it's a h/g failure (I had a new one fitted to it about 2k miles ago).

Cheers (and sorry about all the newbie posts)

[ligertigon]

There may be many reasons for your overheating so its hard to say. Easiest to check are:
(1) coolant level, and bleed out air.
(2) expansion tank cap and tubes, check for splits cracks and that they are the right way around.
(3) Oil level
(4) Check radiator at front is getting hot/warm (this rules out a permanently stuck thermo)
(5) Replace rad cap in engine bay

After that if everything is ok, check timing, and then possibly consider exploring the head gasket!
Running the engine in the temp -red is not a good idea as this can lead to head warpage and ultimate head gasket issues.
My hunch is on 1 or 2 or 5 above.
Interesting tha the gasket was changed 2k ago
Someone else might add anything I've missed

[hachi-roku]

Cheers for the reply.

The car has a new trd rad cap on (well known for adding at least 10000bhp).
Expansion cap and tubes seem ok.
The radiator gets hot, so seems to be working.
The coolant level seems ok, and I don't appear to be losing any but I'll try bleeding some more out, just that it hasn't done any hunting of the idle so I thought it was all out.

The h/g was replaced by the previous owned (who is my best mate so I know it well) it had done about 142k and it just gave up, I know the head was machined to make it true again and he replaced everything.

It has been sugessted that the thermostat might be siezed, but I'd really like to get other ideas before I do that as I have to bleed it all again and fill it up

Cheers.

[snailslime]

I had problems with air in my cooling system not so long ago, heres the thread - http://www.imoc.co.uk/forums/viewtopic.php?t=40615

I think that the air causes the temp gauge to read inaccurately because mine read just above normal while the expansion tank was boiling like a kettle!

[hachi-roku]

Hmm, I think it looks like it might be best for me to do yet another full flush of the system (only fitted a new rad 3 weeks ago or so ) and treat myself to a trd thermostat, may as well as I'm there anyway.

One day I'll get the hang of this car melarky, if anyone wants to help and get cups of tea... feel free

[jimi]

Hmm, I think it looks like it might be best for me to do yet another full flush of the system (only fitted a new rad 3 weeks ago or so ) and treat myself to a trd thermostat, may as well as I'm there anyway.

One day I'll get the hang of this car melarky, if anyone wants to help and get cups of tea... feel free

I'd dump the TRD cap and fit a standard one with a new standard thermostat. The TRd one has a higher pressure rating than the standard one. IMHO there's no reason on a standard engine to fit a TRD cap and 'stat. The standard setup up is perfectly good for normal usage.
Jimi

[hachi-roku]

I still have the normal cap, so I can put it back on... but would having the trd cap make a detrimental effect to the car (don't mean to question... just don't know ).

I had a cunning bit of advice of leaving the rad cap off over night and then top it up in the morning, given that a try now in the hope it makes some difference.

Also the coolant doesn't smell of exhaust gases, definately no mayo and no smoking so I'm praying [-o< that this has ruled out h/g failure

Thanks for all the help.

[MarcsMR2]

having recently gone through this myself, a wise move is to get the system presssure checked, If it's the rad, pipes or worse a cracked block(like mine was) it should show.

I got so fed up with mine I replaced the engine...Fixed the fault!

[MegatronUK]

In good condition the mk1 cooling system is way, way more effective than it needs to be. The stock system coped with my modified 3SGTE perfectly; even when sitting in traffic in my daily commute to work through Newcastle. Temperature has never exceeded half way on the gauge.

[010on1986]

It if often handy when refilling an empty system to note the quantity in litres the system take to refill i.e if you only use 8 litres but it seems full you know you aint there yet.

I would bleed it. Get it hot without the cap on. Leave it to cool, top up. Repeat. Also check for leaks at rad vent and thermo vent (o rings)

[HT]

It if often handy when refilling an empty system to note the quantity in litres the system take to refill i.e if you only use 8 litres but it seems full you know you aint there yet.

I would bleed it. Get it hot without the cap on. Leave it to cool, top up. Repeat. Also check for leaks at rad vent and thermo vent (o rings)

Unfortunately its not that straight forward - as one rarely gets close to 100% out of the system when draining

[010on1986]

How much is left in the system after a full drain?

[Tiamat]

Hmm, I think it looks like it might be best for me to do yet another full flush of the system (only fitted a new rad 3 weeks ago or so ) and treat myself to a trd thermostat, may as well as I'm there anyway.

One day I'll get the hang of this car melarky, if anyone wants to help and get cups of tea... feel free

You did remember to flush the pipes from underneath as well didn't you?

[Polypedates]

How much is left in the system after a full drain?

When we did mine we managed to get just shy of 10l back in suggesting 2 litres remained. And we did use all the drain points including those on the pipes under the car.

Then flushed it twice with water.

It hasn't missed a beat since or needed any topping up.

Running it to hot without the cap in place a did the trick.

HTH

[hachi-roku]

I found out what was causing my heat problems in the end, turned out to be still getting air in from a rusty clip on the bottom lol... fixed it now though, runs like a dream

[010on1986]

Nice to hear its fixed, the reason I mentioned 8 litres is because mine took 8 litres and was full, i vented it and it took another 2! It is all to easy to assume its full when it is nowhere near full, you do need to measure what you are putting back in and query the quantity.

also, nobody seems to mention bleeding the engine block from the drain tap on the block near the oil filter......