[Mk2] [Turbo] Rev3 Head Gasket questions

[millentubby]

Hi All!

It's a bit of a long story but I'm pretty certain the Head Gasket has gone in the Rev3 Turbo engine I stuck in my Rev5 NA. I suspect the HG was leaking into the water jacket a little bit for some time and finally let go yesterday while I was limping to the workshop for yet another fault-find mission & to eliminate the source of air in the coolant being the heater hoses.

The clouds of white steam out of the exhaust lead me to believe I've found the fault!

I've had a good read (Jim-GTS - your write up from a few years ago is great!) of threads and other resources.

Now...I have two questions initially.

1) I'm going to get the head skimmed - How can I tell how much material has been removed from the head already so I can make sure it's still fit for purpose, and can source the correct thickness of gasket?

I believe the HG was done by the previous owner, but since he crashed the donor car in a big way he is sadly not fit to be able to give me any information.

2) Are the (cheaper) HG sets on ebay any good? Or are there definite benefits to sourcing the HG from Toyota?

Many thanks in advance.

Colin.

[Peter Gidden]

1) Get the top to bottom measurement from another head and compare.

Personally, i wouldn't have it skimmed. Have it checked for straightness in all planes and have it surface ground.

2) No idea, i don't trust anything engine-wise to ebay. Most of it is unbranded crap.

If you want reliability buy from Toyota.

It is very rare for a correctly installed OEM MLS head gasket to fail. Ensure both surfaces - block and head - are in mint condition before fitting. And check for a cracked block.

In 9 years I've had 10 plus Rev3 cracked blocks. and NIL blown MLS head gaskets running less than 22-24psi.

[craig]

for the amount of effort to take the head off and replace the gasket, I wouldn't go near ebay for a cheaper alternative headgasket!

Stock Toyota parts all the way.

[millentubby]

Thanks for the replies, guys!

Ok, so Genuine Toyota HG it is.

A cracked block is definately a concern in the back of my mind. Where does it crack, and is it a leak-down test to identify it or can I find it visually once the head is off?

Thanks again,

Colin.

[Peter Gidden]

A cracked block is definately a concern in the back of my mind. Where does it crack, and is it a leak-down test to identify it or can I find it visually once the head is off?

If you know what you're looking for you'll be able to find it.

Take head off.

Inspect head gasket for any obvious staining etc.

Look VERY carefully at the deck surface between the bores for any hairline cracks, particularly between nos. 2 and 3. Turn engine over so each piston is at BDC and look VERY carefully at each bore for any hairline cracks. They are not easy to find, but once you see it, it is obvious.

[millentubby]

Gotcha. Thanks Peter!

Does anyone have an unskimmed rev3 turbo head they could measure as a reference please?

I've got a 3SGE I could measure but I wouldn't want to count on the heads being the same, unless anyone can confirm?

Managed to wrangle the next week off work so I'll have a dig about on the EPC/BGB and see if I can find any useful info.

[Peter Gidden]

Gotcha. Thanks Peter!

Does anyone have an unskimmed rev3 turbo head they could measure as a reference please?

I'll measure you one tomorrow morning.

[millentubby]

Legend- thanks again!

Plan is to drop the engine out Sunday/Monday so I can take the time to thoroughly check it all over.

[Peter Gidden]

Rev3 Turbo head is 119.50mm between top and bottom machined surfaces.

[millentubby]

Thanks for measuring that, Peter, much appreciated!

Got the engine out today- will strip it down tomorrow and report back on the findings.

[millentubby]

In the process of stripping the engine down, noticed numbers stamped on the head.

Noticed some numbers stamped on the head at the corner nearest to the clutch slave cylinder. Reads 11678. I'm hoping that's not the thickness after a previous skim and 116.78mm!

[millentubby]

Head off and positive news- cheap head gasket (not MLS) had been used when previous owner rebuilt the engine, has failed massively.

Bores look clean and happy with no signs of cracks at all (phew!).

Going to order genuine gaskets, head bolts and rebuild. Will clean up the surfaces fully - no sign of warpage on the head at all.

I'll post a pic of the failed HG- had gone completely between 1&2 and was also breached between 3&4, extending to the water jacket.

[millentubby]

Pics as promised;

Now, if anyone reading this thread in the future didn't believe Peter and RedMR2's warning about using cheap gaskets...here's further proof that if you use the wrong sh!t, sh!t goes wrong!







Genuine gaskets & head bolts ordered to arrive tomorrow. Luckily the local Toyota garage is 1 mile from my house and I worked for the company as a partsman so I know who to supply with biscuits to ensure my parts are ordered next-day if available!

Also doing a ball joint whilst it's all apart and replacing the Rev3 Turbo LSD rear hubs with Rev3 Turbo ABS hubs & driveshafts (thanks to Dale aka Hmltnangel) to re-enable the Rev5 ABS.

After nothing but problems with this engine I'm beginning to feel mildly optimistic.

[Peter Gidden]

Did you notice whoever rebuilt the engine has incorrectly re-fitted that cam bearing cap?

I = Inlet, E = Exhaust. Caps numbered 1-5, 1 closest to cambelt with arrows pointing towards cambelt.

I'd be checking everything very carefully in that engine!

[millentubby]

Yeah the cam caps are on incorrectly- the previous owner did the head gasket and timing belt- I had to replace the timing belt and helicoil the tensioner bearing mounting hole.

I was told the prev owner was a mechanic and did the work
himself before he wrapped the donor car around a lamppost and seriously
Injured himself. I can't say a good word about the quality of the workmanship evident, so have been very cautious.

Not cautious enough to do a leak down test on the xxxxxx before I put it in the car the first time, mind!

Do you think I'd do more damage correcting the cam caps or leave them be to minimise damage to the cam and journals?

[millentubby]

Sexy new MLS Head Gasket fitted, replaced other gaskets around the head with genuine toyota ones to ensure future happiness, inspected relatively new water pump and after a thorough bleeding she's running really smoothly. Not taken it very far as I had to do an oil service on my yaris tonight and tidy up the borrowed workshop but initial signs are all good.

Many thanks for the advice, gents!

[millentubby]

So, a couple hundred miles of mixed city and motorway driving and she's still running smoothly.

For reference I measured the head at various points and ended up with a uniform 119.4mm. I measured the head and block for straightness and all was well.

Unfortunately I've had a change in circumstances and am struggling to justify keeping a big toy like this, so it may be I look to move it on after I've enjoyed a few more (hundred) miles in her...just to make sure she's reliable y'know!

Thanks to all again for your valued input!

[kev8611]

Glad to hear you have it running again. By the looks of the block it was a composite headgasket on it and not the multi layered steel one. Maybe why it went combined with previous owners mechanics and maybe not torqued it down properly.Im sure the multi layered toyota ones rarely fail so it should be safe now.

[millentubby]

Glad to hear you have it running again. By the looks of the block it was a composite headgasket on it and not the multi layered steel one. Maybe why it went combined with previous owners mechanics and maybe not torqued it down properly.Im sure the multi layered toyota ones rarely fail so it should be safe now.

It certainly was a composite gasket - and I'm confident the root cause of the failure. I was worried that the block or head could have been damaged but as soon as I saw the poor quality gasket I nearly sh*t myself with relief.

The new HG is still holding up without issue so far - another full tank of fuel run through her this week with lots of sitting about in traffic and a good blat up the motorway the other day - haven't had to top up the coolant, heaters getting hot quickly and staying there and she's pulling beautifully.

I'm beginning to relax when I'm driving the car and starting to really enjoy Turbo engine now!