Thread: head gasket

Originally Posted by DRanged

Thanks for the info mate. Mine seems to be very slowly pressurising at the moment but I will do some more tests. Sounds the same as yours though. I measure the intake pressure at the bend into the inlet manifold, where is your boost guage reading from???

Justin

Same place, except I made my flange, its straight with silicon bend right angle

My ISUZU workshop manual says there are 3 DIFFERENT HEAD GASKET THICKNESSES!!!

You are supposed to measure the distance between the pistons and the block deck, and choose the head gasket according to the smallest measurement.

I can post the gasket markings/pns tonight if anyone wants them. My manual is for 4BD1 and 4BD1T, but doesn't mention any difference between na and t gaskets. AFAIK they are the same.

Don't use a composite head gasked, I have known several which have failed. The genuine ISUZU gasket looks like a bunch of thin stainless sheets sandwiched together.

Originally Posted by isuzurover

My ISUZU workshop manual says there are 3 DIFFERENT HEAD GASKET THICKNESSES!!!

You are supposed to measure the distance between the pistons and the block deck, and choose the head gasket according to the smallest measurement.

I can post the gasket markings/pns tonight if anyone wants them. My manual is for 4BD1 and 4BD1T, but doesn't mention any difference between na and t gaskets. AFAIK they are the same.

Don't use a composite head gasked, I have known several which have failed. The genuine ISUZU gasket looks like a bunch of thin stainless sheets sandwiched together.

if you could post any numbers that would be great. Do you measure all the pistons at their TDC and take the smallest measurement??

Thanks justin

Originally Posted by DRanged

if you could post any numbers that would be great. Do you measure all the pistons at their TDC and take the smallest measurement??

Thanks justin

Yep - that's what the manual says.

Will try and post this evening.

It'll only vary compression..........marginally

Be good if you could post details Ben

Originally Posted by rovercare

It'll only vary compression..........marginally

Be good if you could post details Ben

Might be more to do with varying the valves marginally

Originally Posted by 100I

Might be more to do with varying the valves marginally

WAAAAYYYYYY to much clearance for that to happen

The head bolts for the 4BD1-T are tightened differently to the 4BD1.

For 4BD1:

lubricate bolts with engine oil
1st step - tighten bolts to 6.5 to 7.5 kg-m (47.0 to 54.2 ft lbs)
2nd step - if new bolts, tighten to 9.5 to 10.5 kg-m (68.7 to 10.5 ft lbs)
- if re-used bolts, tighten to 11.0 to 12.0 kg-m (79.5 to 86.8 ft lbs)

For 4BD1-T:
lubricate bolts with molybdenum disulfide (MoS2) grease
1st step - tighten bolts to 7 kg-m (50.6 ft lbs)
2nd step - tighten to 9 kg-m (65.1 ft lbs)
3rd step - tighten a further 90 to 120 degrees rotation

If using more boost, I would recommend tightening to the 120 degrees rotation.

Edit: to convert kg to N (Newton) multiply kg by 9.81