Discovery I Talk about the Land Rover Discovery Series I within.

Head gasket at 237,000

Thread Tools
 
Search this Thread
 
Old Apr 14, 2025 | 07:40 AM
  #1  
WaltNYC's Avatar
Thread Starter
|
TReK
Joined: Mar 2010
Posts: 2,782
Likes: 628
From: NYC
Default Head gasket at 237,000

For years I have been reluctant to say anything about head gaskets as it relates to my truck. It is a 1997 that I have owned since new. I am diligent about maintenance, fluid changes, etc. For the last six months my cooling system has been filling with air when the truck sits for more than a day. The gummy mess on the outside of the engine where the head meets the block pretty much confirmed an external coolant leak. I have been driving around with the reservoir cap just finger tight in order to avoid pressurizing the system. That has worked well, but it was time to fix it properly.

First impression with the intake and valve covers off is that the extensive maintenance has paid off.
 
Attached Thumbnails Head gasket at 237,000-img_2844.jpg  
Reply
Old Apr 14, 2025 | 07:44 AM
  #2  
WaltNYC's Avatar
Thread Starter
|
TReK
Joined: Mar 2010
Posts: 2,782
Likes: 628
From: NYC
Default

We had a little laugh at the visibility of the Land Rover logo on the head from the original gaskets.




Gaskets looked to be in good shape aside from the area around the coolant passages.




The gummy mess of burnt/dried coolant. I ran my finger through it to expose the seam between the head and block.
 
Attached Thumbnails Head gasket at 237,000-img_2852.jpg   Head gasket at 237,000-img_2861.jpg   Head gasket at 237,000-img_2836.jpg  
Reply
Old Apr 14, 2025 | 07:48 AM
  #3  
WaltNYC's Avatar
Thread Starter
|
TReK
Joined: Mar 2010
Posts: 2,782
Likes: 628
From: NYC
Default

One mystery is the engine number. I cannot find it in any of my resources.

Since I am the original owner I can say 100% for sure that this is the original engine (with the original head gaskets).
 
Attached Thumbnails Head gasket at 237,000-img_2865.jpg  
Reply
Old Apr 14, 2025 | 08:17 AM
  #4  
WaltNYC's Avatar
Thread Starter
|
TReK
Joined: Mar 2010
Posts: 2,782
Likes: 628
From: NYC
Default

I noticed that the majority of my valves were pale / white-ish. What does this indicate about the air / fuel mixture? What are they 'supposed' to look like in a perfect world?
 
Attached Thumbnails Head gasket at 237,000-img_2848.jpg   Head gasket at 237,000-img_2849.jpg  
Reply
Old Apr 14, 2025 | 12:35 PM
  #5  
JohnZo's Avatar
Pro Wrench
Joined: Apr 2021
Posts: 1,411
Likes: 397
From: SE Washington State
Default

Good luck with the rebuild! I saw information online that the "fuzzy" crust on the valves indicates some oil burning. My valves looked similar (at 190k) with intakes a bit towards black compared to exhaust. The 50D engine number signifies GEMS 4.0 L (with cross-bolted crank bearing caps). You might know that already. Roverparts still posts parts D1 catalogs (down in the footer) with details about engine numbers (e.g. pertaining to cams).
 
Reply
Old Apr 21, 2025 | 07:35 AM
  #6  
WaltNYC's Avatar
Thread Starter
|
TReK
Joined: Mar 2010
Posts: 2,782
Likes: 628
From: NYC
Default

All done. Replaced the motor mounts which were way overdue. Runs smooth and has a tiny bit more power. When I put my foot on the floor on the highway, it kicks down nicely.

I fortunately replaced all the coolant lines which avoided any nagging leaks upon rebuild.

It is a big/long job, but one that is quite satisfying. I'll get another 150k out of her.


I did not find a ground strap anywhere (aside from the starter). Is there an engine ground strap on a 1997 D1?

Next job is suspension bushings.
 

Last edited by WaltNYC; Apr 21, 2025 at 10:37 AM.
Reply
Old Apr 21, 2025 | 08:09 PM
  #7  
disco96sd's Avatar
Recovery Vehicle
Joined: Dec 2019
Posts: 1,008
Likes: 200
Default

My original head gasket lasted a little over 100k
 
Reply
Old Apr 22, 2025 | 12:02 AM
  #8  
JohnZo's Avatar
Pro Wrench
Joined: Apr 2021
Posts: 1,411
Likes: 397
From: SE Washington State
Default

My '96 has a ground cable from the alternator bracket to the ground post behind the battery, connects then directly to battery negative. I added a strap from the coils (driver side bracket) to a fire wall stud. Don't remember if the head has a spot for a ground strap there, but if it does it is hard to access. Stay calm and Rover on for 150k more!
 
Reply
Old Apr 22, 2025 | 06:45 AM
  #9  
whiskeynipple0088's Avatar
Rock Crawling
Joined: May 2006
Posts: 401
Likes: 55
From: MD
Default

Walt,
any trick to the exhaust manifold bolts - Ive heard they like to break.
Did you replace the cam?
Did you use studs or bolts for the heads?

any other tips and tricks you discovered?
 
Reply
Old Apr 22, 2025 | 08:34 AM
  #10  
WaltNYC's Avatar
Thread Starter
|
TReK
Joined: Mar 2010
Posts: 2,782
Likes: 628
From: NYC
Default

I soaked the exhaust manifold bolts with PB blaster a couple days in advance. Then got the engine hot. Then pulled them once cool. Tough to say with certainty whether it helped, but that is what I did.

No cam change.

I used stretch bolts from the AB kit.

I've read RAVE several times and watched "In Search of the Experience" (can be found in my Google drive), the AB DII head gasket video, and the RSW head gasket video. I also print out all the torque specs of nearly every bolt so that I have them on hand.

Keep all the bolts in their place where possible. If not, bag them and label them.

Use anti-seize on your fan clutch threads.

A variety of different sized extensions for torquing the lower head bolt near #7 cylinder by the firewall is essential. Also a friend to keep their hand on the top of the bolt/breaker bar is a good idea to prevent accidental rounding of the head bolt.

When you are placing the valley pan gasket and tightening the end clamps, put some of the bolts in their places so that you know you they will line up with the lower plenum is installed.

I go through paper towels and cheap micro fiber towels very quickly. I use PB Blaster, gasket remover, and brake cleaner liberally. Cleaner is better.

Put tape over the inlet ports after you place the heads.

Put rags in the stacks when you place the plenum. You don't want any little bits/nuts/anything getting into the intake or cylinders.

Keep the pushrods in the same location they came from. It might not matter, but there may be some specific wear that makes the ends of the rods unique to their location. It may not help, but it won't hurt.

Replace all your coolant hoses and clamps. You'll avoid leaks.

There are some torque differences between the 4.0 and 4.6, specifically on the lower plenum.
 
Reply



All times are GMT -5. The time now is 11:51 AM.