head gasket

[DRanged]

Hey guys

Has anyone got the Isuzu part number for a head gasket for a 4BD1T (is it different to a n/a engine??). Having a few weird problems with pressure in the cooling system since running 15psi boost. have a gut feeling it could be a head gasket. but if someone knows something else pls feel free to enlighten me.

Thanks
Justin

[rangieman]

Hey guys

Has anyone got the Isuzu part number for a head gasket for a 4BD1T (is it different to a n/a engine??). Having a few weird problems with pressure in the cooling system since running 15psi boost. have a gut feeling it could be a head gasket. but if someone knows something else pls feel free to enlighten me.

Thanks
Justin
Pm rovercare he has just been thru this in the last week;)

[rovercare]

No idea if they're different, but compression on these things is that low, one would hope the head gasket will hold up to 15psi of boost and extra fuelling

My head gasket rapidly got worse in less than 3km @ 10 pound, <1km @ standard fuelling <1km 1 screw turn in:angel: and <1km 1 screw turn out, but fresh rebuilt motor :(, all head bolts cracked to release, aside from 2 which were tight, but maybe not tight enough, not enough to lay blame on the builder, the turbo or anything unfortunately.......so no real answer as to why:(, everything straight edged well, I didn't pay to get it built, I bought it rebuilt

But check the pics in my build thread, it was leaking EVERYWHERE:eek:

I've now travelled around 500km @ 15psi and 2 turns out and all seems wellm fingers crossed:eek:

Mine was pressureising the cooling system, so bad, it bypassed the pressure cap and from stone cold, pumped pressure in the cooling system, enough to make the rad hoses rock hard in <15sec:mad:

I will be lifting the rocker gear and retorqueing the head, before I leave for Sydney this weekend

Also I will be replaceing the rocker gear bolts, as one begun to stretch at 20nm:o so they're done as by elbow torque;) cheap **** bolts:mad:

[rangieman]

No idea if they're different, but compression on these things is that low, one would hope the head gasket will hold up to 15psi of boost and extra fuelling

My head gasket rapidly got worse in less than 3km @ 10 pound, <1km @ standard fuelling <1km 1 screw turn in:angel: and <1km 1 screw turn out, but fresh rebuilt motor :(, all head bolts cracked to release, aside from 2 which were tight, but maybe not tight enough, not enough to lay blame on the builder, the turbo or anything unfortunately.......so no real answer as to why:(, everything straight edged well

But check the pics in my build thread, it was leaking EVERYWHERE:eek:

I've now travelled around 500km @ 15psi and 2 turns out and all seems wellm fingers crossed:eek:

Mine was pressureising the cooling system, so bad, it bypassed the pressure cap and from stone cold, pumped pressure in the cooling system, enough to make the rad hoses rock hard in <15sec:mad:
And the PN for the gasket would be?:cool::D

[rovercare]

And the PN for the gasket would be?:cool::D

I don't have a 4BD1t, I have a 4BD1 that I;ve bought a turbo on:p

[weeds]

is the it same engine that is used in the army 110's, if so i should be able to get you a part number...hang on my contact is not working the rest of the week

how quick do you need the number

[rovercare]

is the it same engine that is used in the army 110's, if so i should be able to get you a part number...hang on my contact is not working the rest of the week

how quick do you need the number

If you can find out if the head gasket part No.s vary between the N/A 4BD1 as fitted to the 4x4 and the factory turbo 4BD1t as fitted to the 6x6

[weeds]

If you can find out if the head gasket part No.s vary between the N/A 4BD1 as fitted to the 4x4 and the factory turbo 4BD1t as fitted to the 6x6

yep, i assumed that, was honing around in a 6x6 last night......if i had access to the net and seen this post prior to 10pm last night the part number was sitting on a shelf not 2m away from me

[DRanged]

No idea if they're different, but compression on these things is that low, one would hope the head gasket will hold up to 15psi of boost and extra fuelling

My head gasket rapidly got worse in less than 3km @ 10 pound, <1km @ standard fuelling <1km 1 screw turn in:angel: and <1km 1 screw turn out, but fresh rebuilt motor :(, all head bolts cracked to release, aside from 2 which were tight, but maybe not tight enough, not enough to lay blame on the builder, the turbo or anything unfortunately.......so no real answer as to why:(, everything straight edged well, I didn't pay to get it built, I bought it rebuilt

But check the pics in my build thread, it was leaking EVERYWHERE:eek:

I've now travelled around 500km @ 15psi and 2 turns out and all seems wellm fingers crossed:eek:

Mine was pressureising the cooling system, so bad, it bypassed the pressure cap and from stone cold, pumped pressure in the cooling system, enough to make the rad hoses rock hard in <15sec:mad:

I will be lifting the rocker gear and retorqueing the head, before I leave for Sydney this weekend

Also I will be replaceing the rocker gear bolts, as one begun to stretch at 20nm:o so they're done as by elbow torque;) cheap **** bolts:mad:

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

[long stroke]

I just looked in the parts book and they are about $35 each and i think the part number is 4B2.


TIM.

[weeds]

this is the part number that the army order

and the part number is 8941458390

[rovercare]

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:)

[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.

[DRanged]

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

[isuzurover]

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.

[rovercare]

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

Be good if you could post details Ben:)

[100I]

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

Be good if you could post details Ben:)

Might be more to do with varying the valves marginally:p

[rovercare]

Might be more to do with varying the valves marginally:p

WAAAAYYYYYY to much clearance for that to happen;)

[Bush65]

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

[isuzurover]

OK, Page 6A-107 of the manual (N series, 1985 on).

You need to measure piston PROJECTION from the block deck - at the FRONT AND BACK of the engine (i.e. both sides of a line connecting the piston centres).

3 Grades of Gasket - A,B,C - A has 1 notch, B has 2, C has 3 (in the side of the gasket)

A= 1.55mm B=1.6mm C=1.65mm

Projection MUST be between 0.688-1.000 mm

Max. Piston Projection between 0.688-0.770 Use gasket A
Max. Piston Projection between 0.771-0.812 Use gasket B
Max. Piston Projection between 0.813-1.000 Use gasket C

Sorry but I don't have PN's.

[rovercare]

Seeing as you've got the book out Ben, what's bore size, and I'll find the formulae to work out what difference it makes to compression

[isuzurover]

Seeing as you've got the book out Ben, what's bore size, and I'll find the formulae to work out what difference it makes to compression

Bore x Stroke is 102x118

Using the extreme values, it could vary compression between 16.7 and 17.7:1 (should be 17:1)

[rovercare]

Bore x Stroke is 102x118

Using the extreme values, it could vary compression between 16.7 and 17.7:1 (should be 17:1)

Couldn't see 1 point of compression ratio being the cause, considering its so stupidly low:D

[isuzurover]

Couldn't see 1 point of compression ratio being the cause, considering its so stupidly low:D

I doubt it would have been the cause of your problem - as it was leaking all over the place.

Not sure what you mean by stupidly low??? The LR Tdi engines are 16:1. Most other DI diesels I am aware of are between 15:1 and 19:1 Indirect engines like my 2.25D have ratios like 23:1, but that is pretty high.

[rovercare]

I doubt it would have been the cause of your problem - as it was leaking all over the place.

Not sure what you mean by stupidly low??? The LR Tdi engines are 16:1. Most other DI diesels I am aware of are between 15:1 and 19:1 Indirect engines like my 2.25D have ratios like 23:1, but that is pretty high.

Pretty much that^^^, you wouldn't think the sealing ring would accomodate 17:1 no worries, but then blow out at 23:1 would you

Its not like your adding 15psi to 23:1 therefor increasing static comp further again:eek:

How much does 15psi add to static compression anyway:twisted:

Also almost all direct injection oilers are turbocharged, that I'm aware of

[isuzurover]

How much does 15psi add to static compression anyway:twisted:


Atmospheric pressure at sea level is almost 15psi. So assuming 100% Volumetric Efficiency and 15psi boost at the entrance to the cylinder at the same temperature as an NA engine, you are effectively doubling your compression ratio.

[Bush65]

Regarding head gasket thickness, IMHO people are barking up the wrong tree if they think it is about compression ratio.

With a direct injection diesel, the crown of the piston should be as close to the head surface as practical at tdc. It has to do with squishing the air into the combustion chamber.

IMHO 17:1 compression is good value for a turbo diesel - I don't care about na diesels ;)

[DRanged]

Was talking to some performance guys last night and they recommend if pratical to fit studs & nuts instead of head bolts far better pull down when torqing up. Also they are going to give me the name of a manufacturer of head gaskets to see if a 4BD1T is on their list of modified turbo gaskets.

Worth a look

Justin

[Bush65]

I bought a set of ARP head studs. Think I have posted the part numbers!

[DRanged]

Well got the head off tonight and yep it was leaking on the exhaust side of No2 and a little at No3. have my suspicions it was the head bolts (ie reused when we put the turbo rebuild kit in it) when undoing in the prescribed isuzu manner they were all over the place. Thanks to Bush65 a set of ARP head studs will be going back on.

Justin

[rovercare]

Where's the pics?:mad:

[Dougal]

Not sure how I missed this one, but here's my 2c.

Genuine Isuzu 4BD1T engine gasket set PN 5-87812761-1
The year I quoted was 86 for the engine, this one had the IHI RHB6 turbo originally.

I wasn't given the choice of gasket thickness and I can't see the tab on the gasket with the notches while it's in the vehicle. Two weeks ago I had it out, would have been easy.
Cost me about $NZ300 almost 3 years ago now. It included inlet/exhaust and turbo gaskets, valve stem seals, thermostat gaskets, sump gaskets, crank seals, timing case seals, copper seats for injectors etc.

[DRanged]

Not sure how I missed this one, but here's my 2c.

Genuine Isuzu 4BD1T engine gasket set PN 5-87812761-1
The year I quoted was 86 for the engine, this one had the IHI RHB6 turbo originally.

I wasn't given the choice of gasket thickness and I can't see the tab on the gasket with the notches while it's in the vehicle. Two weeks ago I had it out, would have been easy.
Cost me about $NZ300 almost 3 years ago now. It included inlet/exhaust and turbo gaskets, valve stem seals, thermostat gaskets, sump gaskets, crank seals, timing case seals, copper seats for injectors etc.

Here you go. I was given no choice of head gasket either from Isuzu. Top end gasket kit, as per Dougals p/n $242 AUD. Same here I quoted NPR59 86 model but the Isuzu guy said all the numbers now supersede to a set of numbers which cover a lot of models. No notches or indicators on the gasket. No choice of head gasket for 4BD1T
https://www.aulro.com/afvb/images/imported/2008/07/32.jpg
https://www.aulro.com/afvb/images/imported/2008/07/31.jpg