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what year and model? why are you only replace one? what is the actual reason?
 

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Discussion Starter #3
92' 3.9L Hotwire. Replacing both banks. Whitish smoke from the exhaust and when I was pulling existing plugs on the left bank, I found some rust on the plugs.
 

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I trust you are aware that these blocks can suffer from loose liners (typically after the engine has overheated badly)? The larger the overbore the bigger the issue.

The internet is full of horror stories and it is hard to judge how real this risk is, but it is possible that you change the gasket and then find the issue was with the liners.

You can do a pressure test of the cooling system with the heads off but you have to jerry rig a means to block the openings.
 

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1970-1995 Range Rover Classic
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There's only one factory overbore size, 84mm. Loose liners are totally harmless if pinned, a crack underneath isn't which is why top hats exist. The tooling eventually wore out regardless which is why most liner-only failure stories come from crappy late production Disco II blocks.

OP just change the gasket and do the timing chain\cam\lifters if you've got extra time on your hand.
 

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1995-2002 Range Rover P38A
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I trust you are aware that these blocks can suffer from loose liners (typically after the engine has overheated badly)? The larger the overbore the bigger the issue.

The internet is full of horror stories and it is hard to judge how real this risk is, but it is possible that you change the gasket and then find the issue was with the liners.

You can do a pressure test of the cooling system with the heads off but you have to jerry rig a means to block the openings.

The 3.9 should be ok, it happens, but rare.
The 4 and 4.6 liters are the bad ones... I had/have one.. Wasn't cheap, but a good excuse to put high comp pistons in, balance everything and a mild cam.. ;)
 

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1995-2002 Range Rover P38A
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Have a look at your camshaft for lobe wear.
 

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1970-1995 Range Rover Classic
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I replaced both cylinder heads on my '91 Range Rover over the summer, so I know your pain.
The list of thing to do "while you're in there" could go on forever. I'll break down what I did, and hopefully that can help.
Our vehicles should share the same 3.9L engine; I got a lot of advice to replace the crankshaft bearings, but even with new valves the pressure on mine hasn't been so severe as to blow out the bottom end.
While I was replacing the heads, I also replaced:

Coolant hoses
Hydraulic lifters
Push rods
Valves + valve springs (preinstalled in new cylinder heads, might be a pain otherwise)
Water pump (AZLRO recommends Airtex)
Stepper motor (aka idle air control valve)
Radiator fan
Air intake hose
Air filter
Oil pressure sensor
Coolant temperature sender
Timing chain, crankshaft + camshaft sprockets
AC, alternator, and power steering belts
Spark plugs

and then obviously the head gaskets and head bolts.
Use a 1/2" drive for torquing down the head bolts. I had two 3/8" drive extensions break during the final 90° turn.

I'd also take this opportunity to inspect or replace some other parts in your engine bay. My steering control arm was seriously compromised.
Also take a look at the condition of your cylinder walls. I was surprised to find the crosshatching on mine still intact after 27 years. Before reassembly, make sure the tops of the pistons are cleaned of all carbon and that the cylinder walls are lightly oiled.
If you haven't already, I'd also recommend upgrading your spark plug wires and ignition coil. I use Karlyn-STI 368 spark plug wires; not the best, but affordable and made in the USA.
AZLRO recommends the MSD Blaster 2 for the ignition coil, and Magnacore KV85 spark plug wires. Link is below:

http://www.azlro.org/chad/rrcadvice.html

What really made this job understandable was the factory Range Rover service manual. I found this WAY more helpful than the Haynes manual, and free to boot:
http://www.landroverresource.com/docs/rangerover/Range_Rover_Manual_1992.pdf

For a further breakdown of the engine's mechanics there's a Land Rover-produced manual for overhauling their V8's, which can be found here:
http://www.landroverresource.com/35_39_42_V8_overhaul.pdf

Finally, once everything is back together, don't be surprised if some strange, burning smells come off of the engine. It's all of the oils from the engine and your hands burning off.


Good luck!
 
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