[Mk2] [Turbo] Cracked Block Anyone??

[^Trickster^]

I was hoping the water pump was the culprit of my coolant loss and overheating, however looking at this im thinking maybe not!













Graeme

[Rogue]

Looks familiar...



We've seen probably half a dozen blocks go this way now.

[^Trickster^]

Well I wont be running a thermostat from now on i dont think.

Need a set of 86.5mm cp piston rings if anyone has any

Thanks

Graeme

[Dale_V]

thats EXACTLY where mine cracked

[RobCrezz]

Sorry for your loss


Out of interest, what rev is the engine?

[JJ]

Awww.. Bawls Graeme... I was hoping it would be the water pump passing...

I best check mine !!

Rob, its a rev 1/2 block...

[cantfindausername]

Yeah it sucks anus that this has happened mate. But think you're on the right path for getting it sorted quickly.

[Martian_333]

Sorry to hear that mate

Mines also a rev 1 I thought they were supposed to be the stronger block! is there anyway to prevent this from happening? what causes it - big power builds or just age/both?

[Dale_V]

Sorry to hear that mate

Mines also a rev 1 I thought they were supposed to be the stronger block! is there anyway to prevent this from happening? what causes it - big power builds or just age/both?

i suppose it could be both, plus a few other reasons

when my block went, it was on my totally unmodified rev2 NA/3SGE so obviously it wasnt due to big power

[^Trickster^]

Thanks for the replies guys

Its a rev 1 block, was a rev 1 block!

I have a bare block, and courced piston rings so ill just swap the entire rotating assembly into the block after I have it machined and reassemble it.

I think they go here because the thermostat allows colder water to rush into the block, i think over time and putting more heat in the cooling system via higher power outputs just causes them to wear and break.

The rev1/2 do have thicker cylinder walls but the external casing is pretty much the same, only the later 98+ gte and 5sfe have this part reinforced.

Just one of those things really, I have sourced my parts today so hopefully ill have it turned round in a couple of weeks, its the machine work i have to wait on, engine is almost out now.

Thanks

Graeme

Edit: I will note to people that I built this engine in 2006 and its covered 20k miles of 8krpm and always been 350+rwhp and I always totally kick its head in when i drive it

[cantfindausername]

interesting that they re-enforced that part later on, shows it must have been an issue early on.

[alanmr2turbo]

Sorry to hear that mate

Mines also a rev 1 I thought they were supposed to be the stronger block! is there anyway to prevent this from happening? what causes it - big power builds or just age/both?

No, its the REV2 that had the stronger blocks.

[^Trickster^]

I thoguht the rev 1 and 2 shared the same cast completely and it was only reviewed on the rev 3

Graeme

[JJ]

Similar thoughts to a few of the comments... cold water delivery is on that side of the block... and if running some serious boost .. like a pint glass full of boiling water then chucking it at cold, it'll crack / shatter.

I would have thought a cast iron chunk that like wouldnt have had any issues.. I guess again.. like comment shave been made.. the improvements were made to the later casts...

Matrix ST215 engine any one ??!

Prevention methods ??!?!!

Coolant mix - make sure good quality is used with rust inhibitor... cast iron rusts.... probably take years / decades.... but in an exagerated view.. it'll weaken its integrity with age.

Again coolant mix... good ratio used as it'll stabilise the temperature circulating.... Pure water will fluctuate in temps quicker than those with addiitives.

Buy a 98+ block
Turn the boost down
Run it without a thermostat
Mega Rich tuning would reduce in cylinder combustion temps......
Carry out some heat treating to the block
NDT / Thickness check the cast around that area before building on it...

.
.
.
Just thinking on a little outside the box.... I wonder is it has anything to do with the ARP studbolt fitment... the stud will undergo partial expansion with heat, if the ARP stud is fitted and effectively tightened up against the blocks recessed thread, then potentially, when the stud expands, it could potentially crack the block......

[Chris]

I can see where you going with the cold water theory, however is this not why you warm the car before booting it? Surely if the engine is warmed correctly without boost, this cannot happen? I know mine and AndyF's car have a boost inhibit until our cars hit running temp

I don't believe in thick/thin strong/weak blocks accross the Revisions. I think it is luck of the draw. You either get a good one or a bad one. Mine is currently mapped at 2.6BAR of boost from a GT3582R 1.06AR on a 1994 Rev 3 block. If the thin/thick wall theory was correct, mine would explode!! I have ran it for over 2 years at above 2 BAR on a 3076R prior to fitting the 35R.

I also do not think that running without a stat is the answer. These engines were designed to run at the temp set by the stock stat. This is why I never fitted a TRD stat. Running too cold could cause more bad than good? The block will not keep a constant temp, so will be permanantly expanding and constricting dependant on driving conditions. On these old brittle blocks I really do not think this is the right way.

Just ideas, and I may be wrong.

[Century Motorsport]

Toyota revised the casting on the blocks from 1996 onwards. To do this they must have realised there was a problem.

Look at the head stud around that area, its like it was put on there as an after thought! No where near enough metal around it and is just structurally weak.

I dont put it down to any thermostat issues, I put it down to the luck of the draw and also the condition of the water galleries inside the motor, if there is corrosion then its only going to weaken the block further.

The 1996+ blocks really are ALOT stronger around that area - if you sit 2 next to eachother the difference is clear, for a start it doesnt look like the head stud is out on a limb and its got alot more metal around the water pump - a much better casting and sure to eliminate the issue.

This means you can run sleeves which eliminates cracking of the block internally without the worry of weakening the external strength of the block and pulling the top off it.

Nathan