1hz head gasket

Submitted: Thursday, Jan 01, 2015 at 14:41
ThreadID: 110581 Views:5406 Replies:5 FollowUps:4
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First off Happy New Year to all.
I've had an awfull time of late with my 80 series. (1994 1hz)
First off got a ct26 turbo & huge intercooler fitted. 3" red devil exhaust & egt fitted. Very happy with set up. 48 hours later a 91 year old drove into it. Three weeks in crash repair & shes back looking like new. Four days later the head or head gasket has gone!!!
Egt temps were completely normal. I managed to catch it before it over heated thanks to a watch dog. I'm thinking the very well known 4wd shop has set up the system wrong. Overfueling.
I have had a compression test done prior to turbo fitting & all was good. Also have a boost compensater fitted.
My question is, do i bother getting a refurbished head or take the opportunity to fit a new one? Also once back together, take it somewhere else in Adelaide to be set up properly.
Thanks
Been there done that. Then, been there several more times, because apparently I never learn.

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Reply By: Ron N - Thursday, Jan 01, 2015 at 21:52

Thursday, Jan 01, 2015 at 21:52
Martyn - If you install an aftermarket turbo, the compression ratio should be reduced by the fitting of a thicker head gasket.
I presume this has been done? The crowd fitting the turbo should know to do that.
Overfuelling will be obvious by black smoke pouring from the exhaust under heavy acceleration.
Get someone else to drive the 80 series and get them to accelerate hard while you follow it reasonably closely in another vehicle.
The exhaust should only show a slight haze of black smoke under acceleration.
If the black smoke is thick and very visible while the accelerator is being floored, then it's overfuelling.
The fuel injection pump should have been adjusted to provide more fuel when the turbo was fitted, because the turbo delivers a lot more air than a naturally-aspirated engine can suck in.
However, the fuel delivery has to be in line with what is required for the amount of air available in the combustion chamber.
If the pump has been adjusted up too far, this will then create an overfuelling situation.
There should be no reason to buy a new head if the old head has no cracks or isn't badly warped.
It certainly pays to have the head surface ground, the valves ground and valve guide-to-valve wear checked, when the head is off.

Cheers, Ron.
AnswerID: 543584

Follow Up By: Martyn - Thursday, Jan 01, 2015 at 22:13

Thursday, Jan 01, 2015 at 22:13
Thanks for your reply Ron. There's no sign of black smoke at all. I must admit since the install any smoke has all but vanished. I know for sure nothing was done to the head. Should i go Toyo gasket or upgraded???
Isn't a compensator suppose to take care of over fueling?
Thanks
Been there done that. Then, been there several more times, because apparently I never learn.

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Follow Up By: Ron N - Thursday, Jan 01, 2015 at 22:40

Thursday, Jan 01, 2015 at 22:40
Well, no black smoke means it's not overfuelling.
The boost compensator is fitted to adjust the fuel injected to the level of boost.
It's essentially an aneroid that alters the rack position according to the intake pressure.
No, the compensator isn't fitted to take care of over-fuelling, it's fitted to take care of under-fuelling.
The injection pump still has to be adjusted so the fuel being injected on each stroke, matches the amount of additional air being pumped in.

Aftermarket gaskets are quite satisfactory. AA Gaskets make gaskets in 3 thicknesses. Toyota make them in 5 thicknesses.
The piston protrusion has to be measured when the head is off and the thickness selected according to the amount of protrusion.
I would be selecting a thickness one grade higher than recommended, but that depends on your personal choice and the amount of boost you are running.

Cheers, Ron.

AA Gaskets
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Reply By: tonysmc - Friday, Jan 02, 2015 at 16:11

Friday, Jan 02, 2015 at 16:11
Don't even think about a refurbished head, get a brand new one from All Head Services in Victoria. Ph: 1300 41 61 81. They will send it to you complete with valves and ready to bolt on.
http://www.allhead.com.au/ (Site sounds dubious I know)
I have no connection, just a very happy customer with there price and service.

Cheers Tony.
AnswerID: 543619

Follow Up By: Martyn - Friday, Jan 02, 2015 at 16:30

Friday, Jan 02, 2015 at 16:30
Thanks Tony.
That was my way of thinking. Hopefully will be the only time i get the chance to change a twenty year old head.
Will they supply a thicker gasket aswell do you know.
The mob in Adelaide start work on mine next Monday & i'm sure they just send it off to be checked over.
Thanks
Martyn
Been there done that. Then, been there several more times, because apparently I never learn.

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Reply By: awill4x4 - Friday, Jan 02, 2015 at 17:15

Friday, Jan 02, 2015 at 17:15
Do you know what boost pressure you were running?
Any indirect injection diesel turbo shouldn't be going much past 10-12 psi due to their already high static compression ratio.
Also regardless if you go new head or recondition your old one, get new head bolts and torque down appropriately.
Regards Andrew.
AnswerID: 543623

Follow Up By: Martyn - Friday, Jan 02, 2015 at 17:40

Friday, Jan 02, 2015 at 17:40
Was (supposedly) running 10-12psi as set by 4wd shop in Adelaide!!!
Egt never went over 450c
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Reply By: PhilD - Friday, Jan 02, 2015 at 20:34

Friday, Jan 02, 2015 at 20:34
My 100 series 1HZ has been looked after for the last 14 years by Cross Country 4x4 in Edwardstown, and is still going strong. It has a Schwitzer turbo from almost new, and a Cross Country top mounted inter cooler now days. I suggest you talk to them if they are not already in the mix.
AnswerID: 543629

Reply By: Martyn - Friday, Jan 09, 2015 at 16:12

Friday, Jan 09, 2015 at 16:12
Update on the 80 series head.
4 out of 6 cylinders cracked. So a new head & all the bits is on order. Will be another two weeks as machinist is still on hols.
No idea on dollars yet!!!
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