[Mk2] [Turbo] Rev4 Turbo - HG gone :(

[willfinch36]

Just had a call from Luke @ Pacific Works, seems my HG has gone on my rev4, its only done 54,000 miles running standard boost!

Had a few overheating issues. tried thermostat, bleeding coolant etc.

Just done a sniffer test and its come back with bad results!

What may of caused this? I mean I dont drive it like a total tit, always let it cool down etc.

Greddy Intercooler + rouge downpipe.

Any ideas?

Just would be intrested to know.....

[craig]

Somebody changed the metal HG previously with an incorrect rev 1/2 paper one?

[jon_st205]

No chance it's a cracked block instead? More likely than HG.

[Lewis Jay]

As said, more likley to be cracked block.

Not heard of a Rev 3+ headgasket going before????????

[Rory]

Ouch - A cracked block sounds worse than a hg failure. Aren't cracked blocks hared to identify? Your car is probably too nice to break - maybe look out for a good used engine? Or get Luke to change HG and hope it is just the HG. If he strips the head off will the hg failure be visable?

[Rogue]

Had a few overheating issues. tried thermostat, bleeding coolant etc.

This. ^^

The most likely scenario is that you have a separate fault that has caused the car to overheat which in turn has caused the headgasket failure. Be sure to pressure test the coolant system again once the headgasket issue has been resolved.

[Lewis Jay]

Had a few overheating issues. tried thermostat, bleeding coolant etc.

This. ^^

The most likely scenario is that you have a separate fault that has caused the car to overheat which in turn has caused the headgasket failure. Be sure to pressure test the coolant system again once the headgasket issue has been resolved.

Like a cracked block


Have you successfully cured overheating issues on many rev 3+4`s Patrick, by doing the headgasket or have these always turned into other problems e.g cracked blocks, co`s all the ones I have seen have never been headgaskets??

Surley a pressure test would be the first thing you would do, not the headgasket then a pressure test...........isnt a leak down test more likely to show block and or headgasket issues?

[Rogue]

Have you successfully cured overheating issues on many rev 3+4`s Patrick, by doing the headgasket or have these always turned into other problems e.g cracked blocks, co`s all the ones I have seen have never been headgaskets??

Yes, we've fixed overheating issues on many. many cars of all revisions! Headgasket failure on revision 3+ engines in uncommon, but a lot more likely than a cracked block.

Surley a pressure test would be the first thing you would do, not the headgasket then a pressure test...........isnt a leak down test more likely to show block and or headgasket issues?

Given that the car is at a garage I've assumed that all the correct diagnostic steps have been taken. If a leak in the coolant system has caused the headgasket to fail then there will be two failure points in the system. Once that has been rectified it will need pressure testing to find the second failure point.

I'm not saying the block hasn't cracked, but it certainly wouldn't be my first thought. Given that the head has to come off anyway then a visual inspection of the cylinder walls can be made.

[willfinch36]

Thanks for your input, there had been a leak originally in one of the "pipes from hell", which had been sorted, so thought that would be the end of it, but then it continued to overheat, and also the harder you booted it, the more coolant it pushed out.

[JJ]

Its possible the head has warped during a few cooked moments... I had a scenario with mine where it would boil over.. but never really let it get to a stage where it was seriously blowing out of the expansion tank, as soon as the heater went cold... shut it off...

Took the head off, got it skimmed.. inspected the bores thoroughly... couldn't see anything.... Stuck it all back together... overheated after 20 mins !! Hateful !

This time, I let it boil over properly ( real smart ! ) so clearly showed its weakness .. head back off and a hairline crack was visible !

Often tell tale signs can be difficult for a cracked block unless you have portable X ray inspections tools ( if not visable )

Not the end of the world though, you can soon sleeve the block which although there has been varied opinions, my own sleeved block has proven to be highly durable.

As emphasised by others though, do check for leaks... especially on the block ... Its possible with the previous overheating that has taken place, the water pump has scored its bearings and in turn will leak under pressure.. this causing a trace leak down the side of the block which steaming off or simply poor weather, its not noticable of it ever losing any coolant.

If any advisory, considering fitting a new water pump after any overheating issues on the engine, it'll ensure the reliability of the unit. It is very difficult to tell if the bearings have been scored on the water pump ( dry running )

[greeny]

When my block cracked I dropped then engine and inspected it thoroughly (it was leaking behind the water pump outlet), and couldn't find a thing, apart from a tiny hole in the HFH, so replaced the hose, pressurized the coolant system, reinstalled it all, checked and checked again and back to the dyno. On it's second full boost run it was p1$$ing out coolant again

Did a couple of more runs after cooling down and still the same, back home and stripped again, only to find a crack in the block exactly where I'd inspected it !

The joys of MR2 ownership!

[Rogue]

We use a pink dye that turns white when there's a crack. Don't ask me how it works, I suspect it uses science!

[Steve Horrocks]

We use a pink dye that turns white when there's a crack. Don't ask me how it works, I suspect it uses voodoo!

Fixed it for you.
In all seriousness though, ink tests are good!

[dawesy]

what were the symptoms of the overheating, i have cracked a 3S block andthe car drove fine off boost but overheated as soon as boost was applied. as soon as you lifted the temp went down.
they arnt that hard to see when the head is removed
heres mine cyl 3 next to cyl 2


ive seen more cracked blocks than failed rev 3 heads and at least 3 of them were on std cars too

[JJ]

Dawesy, exactly the same place as 2 of mine !
<<<<<<<<<<<<<<<<< See avatar !

Weak spot in the block, the cast iron is at its thinnest ! I've carried out various NDT / thickness checks in the different bores across several blocks... generally 3.8mm around that region. Other places upto 7mm...

The culprets of cracking the block is often related to tuning and/or quality of the original casting or how central the original boring process is.

One other area is the circulation of coolant around the bores where the high boost combustion can create a sudden spike in temps, the small volume of coolant around / between cylinder 2 and 3 can soon superheat which potentially can cause gassing off... when displacement occurs in the surrounding incoming coolant , the temp differences can also cause us problems > again quality of material in this case... Again, this is all an exaggerated theory.

^^^ Points to tuning, get some more fuel in there !

Detonation can crack a block as well, combustion creates unbalanced harmonics within the block where the frequencies can potentially crack any component > piston / cylinder wall / head / crank. Bottom pulley ( harmonic damper ) usually manages to reduce this.

^^^ Points to tuning, get det cans on it, sensible ignition advance !! If anything averse is happening .. increase air temps ... sort the ecu out to retard the ignition considerably if this occurs or fix the air temp issues. If its leaning, rectify the fueling issues ! Fit water injection for det control.... There are plenty of precautions to put in place, but this will not always 100% guarantee issues.

[willfinch36]

It was a slight leak in the HG after all.....

[sjm1984]

It was a slight leak in the HG after all.....

Head lifting?

[JJ]

It was a slight leak in the HG after all.....

Winner !!

[Lewis Jay]

It was a slight leak in the HG after all.....

Thats a first for me on a Rev 3+ but hey, great news.