Which head gasket?

[jimzzr]

Head gasket went between 3&4 (running on two) and then (or perhaps before to some extent?) to the water jacket. Anyway stopped in a cloud of steam before things got too hot.

Have pulled the head and fortunately no pitting horrors on the block so looks like it will be OK, although I haven't yet checked out the block with straight edge.

My question is basically what head gasket should I go for. The old one measured 1.25mm. The piston bore could be slightly over size maybe 81.4, but I only measured this at the top of the bore with some cheapy vernier calipers in the dark.

I'm looking for reliability not performance gains. I will probably get the head skimmed but I've no intention removing the block.

My instinct is to go with Toyota, but some seem to rate cometic or HKS (but seem hard to find at 1.25 mm).

Finally are the head bolts torqued to yield. The manual suggests re-using, is this a good idea.

Many Thanks

Jim

[mrturbotom]

Genuine and fresh bolts is what I'd choose

[tottacrolla]

Although expensive the Genuine toyota gasket is about the best there is for a standard fitment.
I have always re-used the old bolts and have never had a problem with them.

[PW@Woodsport]

OEM or Payen.

[jimzzr]

I changed the head gasket but still appeared to have a slight leak. Otherwise engine ran fine. Pulled cams and connected air line to spark plug apertures. Couldn't see any trace of bubbles in coolant at cap opening. Slackened off head bolts slightly and re-torqued to 45ftlbs.

Didn't really expect it to work. However, now car won't run t all. Can just about get it to run at part throttle at about 400rpm, pulled plugs on at a time but didn't seem to be related to anyone (or more) cylinder in particular. Compression is a bit low 9-10 bar across cylinders. Plugs looked wet (fuel rather than oil)

My question is the above simply the head gasket or have I caused some other fault?

[PW@Woodsport]

Sounds like your cam timing is wrong.

[jimzzr]

That was my first though but all marks seem to check out OK.

Actually thinking about it I didn't actually check the knock pin positions. If there is more than one punch mark on the pulley, I guess its just concievable I manage to inadvertently rotate the Ex cam fitting the belt. hmm.

[PW@Woodsport]

One pin points up, the other points down, so yes, if you timed the engine with both pointing the same way your cam timing is horribly out.

[jimzzr]

Well re-checked cam timing and was all correct. Didn't remove crank pulley this since last running OK should that be good. To compound my woes I dropped a washer off the cam cover and I'm not sure where it's gone!

I'm tempted to just pull the head again and try fitting another gasket with new bolts. Last time the bolts didn't tighten very smoothly on the 2nd plus 90 degrees. It also seemed to be way above the torque that the Haynes manual quotes. May be I didn't re-torque enough and it's leaking between cylinder, should probably have removed all plugs (not one at a time) when compression tested.

If I'd pressurised the induction side (assuming it's even possible) what could I have damaged?

[PW@Woodsport]

I think to diagnose this further i'd need to get hands on, there are too many variables now.

[jimzzr]

I think to diagnose this further i'd need to get hands on, there are too many variables now.

I'd like nothing more, but unfortunately I'm in kent. I know what you mean about too many variables. I've pull the head again to get me back to where I started and then fix it from there if it needs it.

I did quickly have a look at the map sensor output. Seems to be working OK starts at 3.6 and goes down with vacuum & hols at steady vaccum, but need a vacuum gauge to be certain outputs OK. No obvious sign of fuel in vac line to FPR either.

When attempting to start the car the map reading initially goes low (ecu cuts power?), but then returns to 3.6V. This doesn't seem right to me?

[jimzzr]

Well I'm back up and running again. Head gasket must have been leaking between cylinders. Seems good now but it'll be a good few miles yet before I'll be confident it's fixed.

Why it didn't work first time I'm not sure. Could have been the old bolts - they didn't tighten smoothly (twisting and slip stick). The 22ftlbs +90+90 I strongly suspect is enough to get to the bolts yield point.

Second new gasket ended up as BGA (ordered payen but sent instead), mixed reviews so I guess time will tell. Interestingly BGA is 1.4 mm vs 1.2 standard. Instruction required 49ft/lbs in 3 passes + retorque after running up to temp for 4age but 22+90+90 for supercharger.

This time I went with the old 49 ft/lbs. However, out of interest I did torque to 22 and mark the bolts. Even after re-torque non of the bolts were more than +90+45. The two specs are in no way equivalent.

I did also wonder if perhaps the skimmed head had a too good, almost mirror finish, so gave it a light rub with some fine wet and dry also to lessen marks in head from ist Toyota gasket.