What causes these engines to go through head gaskets so quickly? Or what is the main cause of the head gaskets going bad? is there anyway to prevent it?
7MGTE question?
- Thread starter gmoney
- Start date
From what I've been told and read the factory torque setting on the head was wrong. That is all I know on the subject. I'm sure the others will tell you the exact reasons why.
My Sup went 154k without blowing it. 16k of it was my driving after I bought it. It sat for a while before I bought it so maybe the gasket had time to get soft and corrode. I'll wait and see what they say as well.
My Sup went 154k without blowing it. 16k of it was my driving after I bought it. It sat for a while before I bought it so maybe the gasket had time to get soft and corrode. I'll wait and see what they say as well.
It's entirely torque related. Toyota spec'd the torque at 58 foot/lbs, and analysis of the headbolts by a third party since has told us that 72 foot/lbs is what should have been used.
New headgasket and bolts torqued properly makes for a bulletproof engine - as long as you keep the oil level up.
New headgasket and bolts torqued properly makes for a bulletproof engine - as long as you keep the oil level up.
As GJ says the tq settings used were a bit off!
Electrolysis in older motors that haven't had the correct coolant is also a factor as the aluminium in the head around the water passages is the first to go!
(there are a few of different ways the gasket can "blow" ie: Coolant>Sump
Comp>Sump Comp>Coolant all of em suck though)
Electrolysis in older motors that haven't had the correct coolant is also a factor as the aluminium in the head around the water passages is the first to go!
(there are a few of different ways the gasket can "blow" ie: Coolant>Sump
Comp>Sump Comp>Coolant all of em suck though)
Werd about the low torque setting. I replaced my HG with an oem one and used ARP head bolts torqued to 75ft.lbs. Just make sure you also keep plenty of oil in there. I have replaced all the seals(2 front mains, cam seals, rear main and valve seals) and I still have a little oil consumption(probably from the turbo and/or blowby).
Yep, not clamped hard enough.
One thing: IIRC, 72lbs/ft was based on the yield strength of the stock bolts with the head expansion factored in as well. More than 72 and the risk was high of deforming the bolts after a few heat cycles and losing clamping force. Could be wrong though, please don't :stickpoke if I am.
One thing: IIRC, 72lbs/ft was based on the yield strength of the stock bolts with the head expansion factored in as well. More than 72 and the risk was high of deforming the bolts after a few heat cycles and losing clamping force. Could be wrong though, please don't :stickpoke if I am.
You are not wrong, 72 was the perfect spot for the stock bolts.
Of course, most of us use ARP bolts now, and those are good to 125 foot pounds at least.
Of course, most of us use ARP bolts now, and those are good to 125 foot pounds at least.
GrimJack said:You are not wrong, 72 was the perfect spot for the stock bolts.
Of course, most of us use ARP bolts now, and those are good to 125 foot pounds at least.
but you wouldnt want to torque it down that much on a composite (stock) head gasket! :icon_razz
WOW.. I was correct then. It's good to see I can still put my .02 in and not get slammed.. :biggrinki I'm going to pat myself on the back now and hush. I dont want to shoot myself in the foot by getting the next one wrong. :icon_razz
ive also heard that the reason #6 blows more than most is because of high heat from the EGR and 1st cat
Is it recommended to replace the stock head bolts once used, due to stretch for higher torque, my 3S-GTE (ex All-Trac) the TSRM mentioned that. It also had a different precedure for torquing the bolts, take it to a value and go 90 degrees, that really put a squeeze on the gasket.
William 89T
William 89T
Technically the 7M head bolts are reusable even with the higher torque. 72 ft/lbs still lies within the elastic portion of the bolt. On the other hand replacing them is cheap insurance. Personally I'd replace them.
I think there may be more to it than just the head not being torqued down hard enough. MK4's run 30psi on stock headgaskets with no issues. I ran 24psi with a Greddy metal headgasket and ARP headbolts, and lifted the head off the gasket. I beleive it was heat related more than anything.
well the shop were my car was called me up to tell me my headgasket was fine! it was the head that was shot :thumbsdow but my buddy has an extra engine and i picked up a head with 100,000 miles on it for 150 bucks with the cams and whatnot. so that car will be good tomarrow...
You neglected to mention how much torque you are using on the head gasket. Mk4 is a whole different ballgame, 30psi on a stock Mk4 is nothing like 30 psi on a stock Mk3.MRSUPRA said: