Engine Symptoms - What action to take ?

[LandRoverGhost]

Hi Trols,
My 1990 TB42 is showing signs of old age now.

Technical:

• Dual Fuel
• Electronic ignition (Pirhana)
• Carburettor (Nikki)
• New ignition leads (Eagle)
• New Coil (Magnecor)
• Always clean airfilter (K & N filter )
• Variable LPG flow mixer ( BLOS )
• Variable LPG / Petrol timing (Auto retard on Petrol)

The symptoms:

• Starts almost always very good , as if a light switch is flicked over.
• 'By ear' it runs reasonable smooth well as well on LPG gas and Petrol. A slight irregular beat when I really put my ears to it (Very old ears)
• Climbing our steepish mountains in the Warrumbungle Ranges is becoming a real drag. Near the top of a very long steep climb ... out of puff to near standstill.
• Does not use any oil of significance between changes (7500 - 10000 km)
• When changing oil the colour is still reasonable clean (Not even close as black as with my old Land Rovers in the past)
• Uses an amount of coolant , 1/2 liter or more every 2500 km I guess.
• Clean looking exhaust fumes.

Diagnosed:

• Owned since 2016 and do not drive a lot but we live remote so I drive only longer distances - I notice the engine running at its best after about 20 minutes.
• 400000 km done ( I think ... previous owner mentioned some speedo issues in the past so it will most likely be more)
• Compression cold and dry: Cyl 1 130 PSI // Cyl 2 130 PSI // Cyl 3 130 PSI // Cyl 4 ... 40-50 PSI .... // Cyl 5 120 PSI // Cyl 6 145 PSI
• Compression cold and with squirt of engine oil:: Cyl 1 150 PSI // Cyl 2 150+ PSI // Cyl 3 150+ PSI // Cyl 4 ... 40-50 PSI .... // Cyl 5 130 PSI // Cyl 6 155 PSI
• Repeated compression test next day not having run in between, almost the same results as when done immediately after oiled test.
• Spark plugs: Cyl 1 blackish // Cyl 2 dark brown // Cyl 3 very rusty as if heavy corroded // Cyl 4 lighter brownish // Cyl 5 brown // Cyl 6 blackish
• Strong Sparks
• No disturbing noises

What to do?
As said before : Serious lack of torque climbing steep mountains or towing anything - near zero oil usage.

My question is : What do you suggest to get at least a bit more torque and stop that coolant loss ?

Thanks !

[mudski]

Head gasket leak on number 3? Replace the head gasket and get the head crack tested at the least I would do.


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[garett]

i'm with mudski on this, the wet compression test suggests upper cylinder (valve or head gasket maybe crack need to take it off) in cyl 4 is leaking and the rusty spark plug on 3 i would say thats where the coolant is going,

[LandRoverGhost]

Thanks - that sounds like a good start.
I only have experience with 2x a Land Rover V8 head replacement.
Are there any pitfalls to be aware of with this job ?

Head gasket leak on number 3? Replace the head gasket and get the head crack tested at the least I would do.


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[LandRoverGhost]

Thanks - sounds like a plan.

i'm with mudski on this, the wet compression test suggests upper cylinder (valve or head gasket maybe crack need to take it off) in cyl 4 is leaking and the rusty spark plug on 3 i would say thats where the coolant is going,

[mudnut]

Get a set of new head studs. Lop the head off two old ones and, grind a bit of a chamfer around the top, then grind a slot in the top for a screw driver. When you are ready to refit the head, screw these modified studs loosely into the block. These help hold the head gasket and guide the head into position. It is then easy to un screw them. A bit of extra work but it will save you crimping the new gasket.

[LandRoverGhost]

Thanks ! That is a good advice. Easy to do.
With the V8 heads I applied a thin coat of Hylomar to the gasket - was recommended by an old Land Rover mechanic. Does that make sense for this job as well ?

if I have to buy a new head - any suggestions of a good supplier? I am 100% reliant on online purchase as I live quite remote in Central NSW but are reluctant to buy off eBay.

cheers, Jacob

Get a set of new head studs. Lop the head off two old ones and, grind a bit of a chamfer around the top, then grind a slot in the top for a screw driver. When you are ready to refit the head, screw these modified studs loosely into the block. These help hold the head gasket and guide the head into position. It is then easy to un screw them. A bit of extra work but it will save you crimping the new gasket.

[mudnut]

Dunno about the Hylomar. Patrolapart do heads. Click on the Patrol Parts button at the top of the page. Type in Tb42 head in their search bar and you will see a few options.

[garett]

i've used hylomar before, if the head is machined properly and the top of the block is nice and clean, theres not much point, not with these if u use a quality head gasket.
i would also suggest a new set of spark plugs if it isnt on ur list .. gas is harder to ignite then petrol, on a side note i have seen a tb45 on gas, they only ran gas and no petrol, gummed up some valves and it dropped the push rods.... use some petrol to keep the carby working and valves clean .

[Pete49]

My '92 tb42e did a haed gasket in a similar way as yours. The head checked out ok so while I was at it I decided to replace the rings and bearing.(450k motor) did it with the motor in place and total cost for every thing was about $250 for parts. Now pulls like a train and smooth as silk.
Pete