Head gasket leaking again!!!!! 3.9 v8

Bushcrusher · Oct 13, 2022

Good morning guys, can somebody please help me with this? I changed my head gaskets over a year ago. All eas going well then noticed she was venting coolant from header tank. This sounded like a boiling kettle so straight away I knew exhaust gases were getting in. Did the exhaust gas test and yes it is, my dilemma is as follows the gaskets listed for mine are composite (1998 3.9 with serpentine belt)
I did read somewhere that I could use the 3.5 v8 gaskets and these were metal (looked metal) and this would be the best option to stop composite fails. Is this true? And would I have to make any changes to holes in gasket. I really don't want to do this again as it's a bugbear. The engine DIDN'T OVER HEAT the temperature guages (I have 2) didn't go past normal running temperature
So any advice would be greatly appreciated
Many thanks
Dave

norseman · Oct 13, 2022

That's strange, I would have thought that composite would have been given a better seal than metal. I had my 3.9 done with them & had no problems though they do result in a slight reduction in compression ratio, which was probably better, back in those days, for running on standard 95 unleaded.
Perhaps the heads need skimming.

kermit_rr · Oct 13, 2022

I thought the composites were better too.
If the surfaces are flat and clean then shouldn't need skimming.
3.9 block is bored out the same as the 4.0

some it suffers the same issues

Henry_b · Oct 13, 2022

Composite are far superior, tin gaskets are a waste of time.

Inferior quality gaskets, or the stretchbolts which can vary dramatically depending on manufacturer, some stretch too soon and you get the HG fail or they are to hard and you end up ripping threads out the block if you do the job again I'd recommend you ARP stud it.

On and being that you'll have the 14 bolts heads, the lower most head bolts or studs just tighten them to 25lb'ft if you torque these up to spec you'll unevenly load the head and you'll get a very slight HG leak in to the V very common, one of the reasons LR changed the heads on the GEMS V8 to 10 bolt

Ratae · Oct 13, 2022

When I did the top end of my 3.5EFi a couple of years ago I used Elring composite head gaskets.
I had an inlet manifold to head bolt (front of the right bank) shear when I was removing it & after a bit of thought decided the safest option was to take it to a local engine rebuild specialist.
Checking that head showed a very slight warp & I took the other one in as well. Very slight warp too.
Both skimmed.
The original gaskets were tin but as I replaced the cam at the same time I can't say I noticed much difference - bearing in mind this is a vehicle with the aerodynamics of a garden shed & not a sports car!
Don't bother with the third row of bolts - even if the holes are there - but if the holes really bother you just nip them up.
I used a composite on the inlet manifold gasket too - plus blue Hylomar round the water ports.
No issues............so far......

ETA I should add that I'd had no issues with the original tin head gaskets.

norseman · Oct 14, 2022

If I remember correctly the use of composites reduces the CR to something like 8.75 (from the original 9.35) & in day-to-day usage I can't say I noticed any subsequent drop in performance.
My 3.5efi auto has done 61k from new & when I first read about the 'outer row' of bolts I considered loosening them, but then decided to leave well alone. As they say ... if it ain't broke don't fix it

kermit_rr · Oct 14, 2022

norseman said:
If I remember correctly the use of composites reduces the CR to something like 8.75 (from the original 9.35) & in day-to-day usage I can't say I noticed any subsequent drop in performance.
My 3.5efi auto has done 61k from new & when I first read about the 'outer row' of bolts I considered loosening them, but then decided to leave well alone. As they say ... if it ain't broke don't fix it

Skim the heads

Ratae · Oct 15, 2022

^^^But don't go too mad!
I read on a site - I can't remember which one - that someone took a lot off the heads & just couldn't get the vehicle to run right until they replaced the heads.

Gord Wedman · Oct 17, 2022

Ratae said:
^^^But don't go too mad!
I read on a site - I can't remember which one - that someone took a lot off the heads & just couldn't get the vehicle to run right until they replaced the heads.

If you skim too much the intake manifold will not line up correctly.

Scotiawhiskers · Nov 3, 2022

Henry_b said:
Composite are far superior, tin gaskets are a waste of time.

Inferior quality gaskets, or the stretchbolts which can vary dramatically depending on manufacturer, some stretch too soon and you get the HG fail or they are to hard and you end up ripping threads out the block if you do the job again I'd recommend you ARP stud it.

On and being that you'll have the 14 bolts heads, the lower most head bolts or studs just tighten them to 25lb'ft if you torque these up to spec you'll unevenly load the head and you'll get a very slight HG leak in to the V very common, one of the reasons LR changed the heads on the GEMS V8 to 10 bolt

+1 on the ARP kit. All goes together beautifully and no feeling of strain on the studs / nuts. Leave it overnight between stage 1 and stage 2 torque, no need to wait on stage 3 though.

Bushcrusher · Nov 3, 2022

Scotiawhiskers said:
+1 on the ARP kit. All goes together beautifully and no feeling of strain on the studs / nuts. Leave it overnight between stage 1 and stage 2 torque, no need to wait on stage 3 though.

Hi buddy, really want to know about the arp kit. Could you help me go through this as it sounds far better than the standard way.
Would really appreciate it if you could fella
Thanks for a top response. Every day is a school day

Scotiawhiskers · Nov 3, 2022

Bushcrusher said:
Hi buddy, really want to know about the arp kit. Could you help me go through this as it sounds far better than the standard way.
Would really appreciate it if you could fella
Thanks for a top response. Every day is a school day

This kit is what we got for our 4.0 https://shop.v8engines.com/arp-head-stud-kit-35-39-40-42-46-908-p.asp

The studs have a coarser thread on one end, to go into the block, just finger tight. There is a small allen head at the top so you can turn them in easier, but you shouldn't actually tighten them with that according to the instructions.
You can do the studs first, then put the heads on, or locate the gasket on the dowels, put the head on, then put the studs in.
Then the washers and nuts, first stage torque is 25lbft IIRC, all on finger tight, then torque in order to that level. Leave it overnight as aluminium head / block combos will settle slightly. Learned that on my Guzzi - stage 1 torque, leave overnight, stage 2, head nuts still tight at 500miles. Do stage 1 and immediately go to stage 2 by 500 miles some would be barely finger tight, others way below correct torque.
Following day torque in order to stage 2 - 50lbft, then again immediately to stage 3 - 70lbft.
The nut threads are much finer, so clamp more precisely to the torque setting instead of the coarse thread and angle tightening of the standard stretch bolts.

Bushcrusher · Nov 6, 2022

This sounds the way to go for me. Have you a link to where I can get them?
Really appreciate you taking the time and trouble to help me .
Thank you so much buddy

Bushcrusher · Nov 6, 2022

Doh I speed read mail. The links at the top doh

Head gasket leaking again!!!!! 3.9 v8

Bushcrusher

Active Member

norseman

Well-Known Member

kermit_rr

Very

Henry_b

Think outside, no box required.

Ratae

Well-Known Member

norseman

Well-Known Member

kermit_rr

Very

Ratae

Well-Known Member

Gord Wedman

Well-Known Member

Scotiawhiskers

Well-Known Member

Bushcrusher

Active Member

Scotiawhiskers

Well-Known Member

Bushcrusher

Active Member

Bushcrusher

Active Member

Similar threads