I have a 2004 Disco w the 4.6 V8. Ever since I had the head gasket replaced I have had horrible overheating problems. My mechanic has tried everything that this forum has suggested still overheating.

Then I found this:
The overheating RoverEngine.
The overheating Rover engine

In paragraph 6 he states : The cylinder head gasket.

Hey, that's my favorite one. The Rover engine has a special design fault in his heads.

(picture of the 14 bolts and the sequence they are to be bolted)

torque sequence

The heads are held on by 14 bolts. The problem lies in the bolts 11-14. When they get tightened they put an load on the upper bolts, raising the heads by a slight amount. New engines are tight but as the engine gets older the heads allow hot gasses to enter the engine,oil and water galleys. This normally occurs only when high pressures= high load is applied on the engine. Those hot gasses do all sort of mess inside:

- They heat up the water. Even a small amount rises coolant temp dramatically. As this occurs only under load it's difficult to diagnose.

- They are responsible for oil leaks. Oil is pressed out by almost any seal as the vents can't take that much. Hard to find.

- They make black sludge as they burn the oil. This sludge prevents the camshaft from being lubricated. Lobes wear off and power drops.

A good indication of this blow-by is that the tin seal plate in the V makes a bulge as it's pushed up by the pressure. You can see this plate from front or rear under the intake manifold.

There are several possibilities to remedy this. You can take out the offending bolts without any drawbacks (that's what I made). The 4.6 engines and heads don't have this row anymore while the rest of the engine is pretty identical. Or you can fit an composite gasket from RPI in place of the standard metal head gasket. This gasket doesn't have the holes for those bolts either. This gaskets seals much better but also drops compression by a small amount.

Look at RPI's page for some good pictures of this.

Could this be the cause or is this guy nuts?

 

This is a clear case of the cylinder head being warped...... its the most common happening after overheating , very few get away from this disaster....

have you had the head skimmed by a specialized machine shop ...( see attached )

you can change 100 gaskets , and tighten bolts with the worlds strongest man...
its not going to work ... if the head surface is not level you cant solve this problem...

an i do agree with a correct torque sequence of the bolts , it is done this way to prevent pinching of the gasket , and for proper sealing... but its only effective if the surface is perfectly level ....

 

Thank you justryan for such a quick response.

I should have been more clear. Originally the mechanic sent the head to get milled. Still overheated. Sent back and they re-checked. Said it was straight w no cracks but we put a new one on anyways.

My Question is will removing bolts 11 thru 14 (like the article I quoted) actually help? Has anyone ever heard of this before ( I can not find any OTHER reference to this)? Is this guy nuts?

 

Uh huh. Chuy I'd like to see them remove something that doesn't exist. Your heads are 10 bolt heads. Instead of checking the heads for cracks how about checking the block instead..... common area on an 04 is between the head bolt holes and the cylinder liners or the liners themselves. Apparently your "mechanic" isn't one to double check others work, use of a dial indicator is all they need and most real mechanics own at least one good mount and dial, dial calipers and a bore gauge or two.

What brand of head gasket are you paying for?

 

Chuy, make sure your mech is using new head bolts too. They are Torque To Yield and are one use only, clamping force is greatly reduced if used over again not to mention the chance of snapping one inside the block..... If your mech doesn't find any obvious signs of block deck cracks at fore noted places and a liner hasn't become your leakage issue try using Felpro head gaskets, far better than the standard Elring, Victor Reinz, sets. Also the machining work done to the heads has to be mirror smooth, no tooling marks whatsoever.

 

i agree with the above suggestions/post...

Ok this may sound silly ...but hear me out ,

when you say its overheating ..... what signs did you see ...to make you say it was overheating.....

is it the temperature gauge ? is it losing water , is the hood getting really hot ?

help us to help you .......

 

That whole statement is only try on early LR, all 4.0 & 4.6 are 10 bolt. If your heads have been decked and new head bolts have been used everytime. It leaves two possiblities a bad block or the heads here milled to much.

 

Wow so much help. I did not expect this. Thank you everyone.

ihscouts: Block has now been checked and looks good and the liners were checked for movement and are fine; the head gasket is the cheapy tin one (if we pull it apart again I will get the composite); mech is using brand new arp bolts.

justryan: by overheating I mean that the temp gauge starts climbing, you can smell the anti freeze/coolant and usually see steam when I pull over. I have never driven it any more and has had it towed to the mechs on several occasions.

drowssap: thank you. I was very confused. That helped.

So for the update, the mech has gone through everything again. Flush and check the cooling system, made sure there was no coolant in the cylinders, ect. As of now it looks like the problems are fixed. I should get if back this week. I am going to drive the poop out of it to try to get it to do it again. Wish me luck. I will update next week.

Once again, thank you to everybody. I did not expect this much help.

 

You say he ia using arp bolts, bolts or studs? If studs you can rule out the heads be milled to much, but not if bolts are being used. Good luck

 

lets hope its fine now , good luck with that head gasket ...