KevinInSac

So the first time it went, it was my fault. Water in the intake, what can you do? So, that was at 198K. I fixed it. Rebuilt the top end as best I could. Put her all back together and it blew at 202K now. Just started it up one day and it was gone...

I've got a question or two. Am I going to need to have the heads resurfaced again?

I replaced virtually everything you should when doing a HG job, is there anything that I need to replace again?

annoyingrob

If I'm installing another head gasket from the same manufacturer, I don't usually resurface the head.

Replacing the head bolts might be a good idea though. People say that you can re-use them, but after 200k of holding a head on, IMO, they're worn out. what's a few hundred bucks to install a nice set of ARP head studs.

89whitetoyota

did you use Brawny for a head gasket? Unless you over tourqued or didnt follow proper tourque pattern I dont see why it would go out again. Maybe something is warped or cracked?

seaofnames

ARP studs, toyota gaskets. Follow torque specs/procedures.

KevinInSac

I installed new bolts. Used a combo of head gaskets. One brand on passenger and another on the driver. It just worked out that way. This time, I'm going Toyota on both sides... I'm most likely going to get new head bolts and gaskets.

ovrrdrive

Supposedly the head bolts on the 3.0 are TTY and have to be replaced every time you torque them down. As for the gaskets, every gasket in the engine is a throw away.

I also agree that something had to have been done wrong for the gasket to fail again so quickly. Make sure you have everything checked.


At least the job is fresh in your mind...

TNRabbit

I had the same thing happen about 8k miles after a complete rebuild. I think I've traced it down to overly high compression (210 psi) without adjusting the VAFM (to richen).

https://www.yotatech.com/forums/f116...perate-123651/

KevinInSac

Were you at 210 psi in all cylinders?
I'll check mine later, she's gonna sit for a little while right now.

TNRabbit

Between 205 & 210 in ALL cylinders. I think when the dealer did the HG recall in 1999 (92k miles) before I bought the truck, the took a good bit off the heads....

KevinInSac

Hmm. Well, I'll probably be doing the full test and diagnosis this weekend, hopefully. Till then, the truck is going to sit in front of the house.

KevinInSac

She was moved into the garage a week or two ago. I determined it blew in the same cylinder (wet spark plug). I am going to pressurize the cooling system some time soon. That'll tell me for sure. Assuming it's the same cylinder again, anything special I should look for?

Matt16

I've heard that the torque specs on one of the Supra straight 6s wasn't sufficient for the non-asbestos headgasket. To make the HG last, ARP head studs are used and the nuts are tightened over spec (the studs can apparently take it).

I can't see how over tightening the bolts is going to adversely affect the head-gasket per se. With head bolts, there is a real risk of bolt failure.

FredTJ

As already mentioned, use quality gaskets, new bolts and torque in the prescribed sequence.
You did take the head to a machine shop and, not only resurfaced it, but also had the check it for straightness and cracks ?



Fred

KevinInSac

Of course. 6 valves even needed replacing. I am going to take the heads back to him, again, just to play it safe. I've already got the $300 yota gaskets too. Hopefully they work a bit better.

KevinInSac

My dad suggested that it could also be a faulty injector. I considered this and it could be a possibility. For one, he broke the clip for the harness on the very cylinder I suspect is blown (wet/dirty plug). Is there any way to test the injector with out starting the truck? I still want to stay on blown HG alert right now and run the truck as little as possible.

KevinInSac

One of those work days that raises more questions than answers. Pressurized the cooling system, and it was able to hold 13 psi for a long time. Did a compression check, and got some strange numbers:

FW
90 80
88 128
70 124

FW=Fire wall.

So, we had been thinking all along that the T-belt tensioner may not have been tightened properly. Would these symptoms be a cause of a slipped T-belt? (I'm gonna spend sometime searching right now.)

toyota4x4907

I dont think a slipping t-belt affects compression...

KevinInSac

It would if the timing was off, causing the valves to open before the piston is at the top of it's stroke.

toyota4x4907

oh right. I forgot about the cam(s)......

1stgen4gunner

The factory has you torque them down to 80, torque them down to 90 and you shouldn't have a problem.