Boiling coolant - HG?

[Martian_333]

Question for all you fellas

After a 20-30 min run (and I mean not driving hard, normal driving) when I park up I can see the coolant boiling in the expansion tank, if you were to take the cap off the rad (not a great idea I know) its like a kettle and coolant eventualyl boils over.

I've bled the system and the rad gets hot, hot air also blows out the vents no problem (thermastat is working, its almost brand new anyway).

Could this be one of the following things:

1. Rad cap (its the original but I noticed no steam coming out of its sides??)
2. Head gasket (theres no tell tale signs such as mayo, oil in the coolant or smoke - but I am running a stock Rev 1/2 HG)
3. Air in the coolant lines still????
4. Leak in the coolant pipes?
5. Cracked block (/cry)

Question is, do you think it would survive a drive (following a thorough bleed) to the nearest back street garage for a leak down test?

If the coolant pipes were leaking surely I'd notice coolant on the floor.

Cheers

[Slarty]

1) Possible. If it's not sealing correctly the system won't pressurise and hence have a lower boiling point.

2) Very likely. Of all the H/G's I've personally seen fail, none have been between the oil and coolant galleries which would lead to cross contamination and the mayo situation. If it's failed between the combustion chamber and the water jacket the coolant system is getting boiled...

3) Possible, but it sounds like you have the system properly bled, hot radiator etc.

4) Doubtful. True it would introduce air into the system but you'd more likely see the car overheating while driving due to lack of coolant.

5) Doubtful but it does happen.....even on standard cars (I've heard, not experienced)


Get a new rad cap and pop it on. If it continues........it's likely to be a BHG.

Hope that helps

[Martian_333]

Thanks mate, good info

TBH the HG is next on the list to be replaced so it wont be a big deal if its that as I was going to slap on a cometic anyways but the rad cap is cheap so I'll get one ordered next week, if anything it'll add some TRD branding to my engine bay!

The HG I wanna try myself definately, just worried about remembering how everything goes back together! Any tips?

[redmr89]

if your worried aqbout getting everything back how it was.. take pice of it all as u strip it down..( i did last time if u want pics)

im in the same boat here mate my engine is useing water and i think its the hg.. im gutted cos its my daily driver and cant afford it to be off the road. .... but it will give me a chance to do metal hg and stronger head bolts. and maybe some wilder cams.

[toxo]

Are you not just talking about the coolant bubbling into the expansion tank? Happens on all turbos when you switch off (unless you use a turbo timer)...

[Martian_333]

Yeah mate it bubbles in the expansion tank, like a kettle, but it also does it under the rad cap, if you take off the cap the coolant is boiling inside and steam is coming out, its literally like looking down into a kettle. It has never done it that severe before and we are talking 15-20mins of normal driving, I'm pretty sure if I drove it any longer it would blow off the expansion tank lid. Sometimes you can hear it from the drivers seat.

red, that would be pretty awesome if you still have the pics! would you mind emailing them onto me?

Cheers guys

EDIT: Red, I planned on getting Arp headbolts, new gasket seal kit and a cometic hg and I also hoped to do the valve stem seals at the same time. lol all good fun eh

[redmr89]

yeah mate ive still got the pics. its when i stripped my engine after the main bearings decided to spit themselves out and wreck everything. lol

i took pics before i removed any parts, then after every part i took off i took another pic.

im gonna upload em to photobucket and post the link.

they might be of some help.

its a rev1 turbo.

[redmr89]

http://s199.photobucket.com/albums/aa57 ... 0stripped/

hopefully that will work.

[Martian_333]

Excellent pics mate, thank you very much

You certainly went to town there with your engine, what exactly did you do and how long did it take?

Any ideas roughly how long it would take to do the HG (first time around)?

Thanks again mate

[Race Idiot]

Are you not just talking about the coolant bubbling into the expansion tank? Happens on all turbos when you switch off (unless you use a turbo timer)...

I've only had that on two occasions, once when I got stuck in traffic for about 4 hours and the second when I drove across hertfordshire on nsl b roads.

This was even after several minutes of cool down driving and about a minute or so of idling before shutting the engine off. Although this is what I do on pretty much every drive, man I realy need my oil temp/pressure gauges.

[toxo]

I've only had that on two occasions, once when I got stuck in traffic for about 4 hours and the second when I drove across hertfordshire on nsl b roads.

This was even after several minutes of cool down driving and about a minute or so of idling before shutting the engine off. Although this is what I do on pretty much every drive, man I realy need my oil temp/pressure gauges.

That's interesting - I get it pretty much every time I shut my engine off. I generally do 5 minutes of cooldown driving and idle for ~30s before switching off, still happens. Mind you even after driving gently and idling for a short period of time my inlet manifold is still glowing...

I didn't used to with the turbo timer, which did used to run down until the manifold wasn't glowing anymore but that could've been upwards of 3 minutes sometimes and that's heatsoak central.

[Martian_333]

I noticed also the following day it had taken alot of coolant from the expansion tank, assuming it keeps doing that, does that suggest a leak?

Sorry if this is a stupid question, I'm just trying to learn

[redmr89]

no probs with the pics mate.

like i said i stripped it down cause my main bearings decided to disintegrate and distribute themselves round the engine. scoring everything in there path.

so my engine got...

a rebore
new pistons
new rods
reground / balanced crank.
new shells (crank, main, etc)
new rings
skimmed head
cleaned and reground valves
new valve stems
light port and polish of head
new cambelt
new water pump
it was a while ago but im sure i did the oil pump too
flywheel resurfaced.
cams cleaned and checked for tolerance
block acid bathed
rebuilt to toyota spec with new gaskets, filters etc etc.
probs loads of other parts just cant rememeber right now.


it ran fine during run in. and about a month later the turbo decided to blow its seals, and blades spitting metal into the engine again...

bottom end needed doing again so i jst bought a replaicment engine for cheaper than my rebuild and got a ct20 turbo. and its lasted 5 years till now when i think my hg has gone. its useing half a litre of water a week. and after a high boost run its now boiling water out, and p1$$ing water all over my garage floor.

maybe its time for another head gasket and maybe i'll put on my ported head, with a cometic hg and uprated head bolts.

long term i still have the original engine. maybe i should rebuild that with forged components and put that in.

or buy a honda civic 1.4 and just foget about m2's??

not tryin to put u off mr2's ive just had a bit of bad luck maybe.

[Caz]

Sorry to revive this, but my car started doing the same thing last night after an hour long journey at NSL. It was really loud when sitting in my drivers seat and seemed to boil and stop and boil again for a couple of minutes. The engine temp was normal though and I have a turbo timer. Did just under 1000's miles hard driving couple of weekends ago in Ireland and had no real problems with the car.

Going to look more closely tomorrow, as it was pitch dark last night and bleed the system. Is a blown H/G going to manifest itself in any other way without looking in the engine (I will), just to give me a heads up if I'll need to dedicate my day to this and maybe not have one 2 many tonight?!

Thanks for any help

Caroline