Blown Head Gasket Options
#12
01-10-2022 | 10:38 AM
Rock Crawling
Joined: Jan 2011
Posts: 499
Likes: 141
Nice looking truck. Speaking of expensive parts installed those 16" factory steelies cost about a million dollars if they can be found at all. What tire size are you running? 235/85?
#13
01-10-2022 | 10:39 AM
Thread Starter
|
Mudding
Joined: Dec 2018
Posts: 114
Likes: 7
From: Anderson, South Carolina
The following users liked this post:
mollusc (01-10-2022)
#14
01-10-2022 | 10:41 AM
TReK
Joined: Sep 2020
Posts: 2,372
Likes: 569
From: British Columbia Canada
The following users liked this post:
chandlerhayes01 (01-10-2022)
#15
01-10-2022 | 10:45 AM
Thread Starter
|
Mudding
Joined: Dec 2018
Posts: 114
Likes: 7
From: Anderson, South Carolina
#16
01-10-2022 | 11:17 AM
Rock Crawling
Joined: Jan 2011
Posts: 499
Likes: 141
Cometic makes MLS head gaskets for Rover V8's in both a 96mm and 94mm bore as well as various compressed thicknesses last time I looked. You can look on the Summit website and see what all is available.
The 4.0 and 4.6 blocks, according to spec, use a 94mm bore. The liners also apparently sit on a lip at the bottom, preventing them from moving downward into block, but nothing preventing them from moving up to the top besides the head/gasket.
In theory, if the liner is already fully seated against the lip at the bottom, and you use a 94mm Cometic MLS gasket, it will prevent the liner from moving completely.
I have some Fel-Pro composite gaskets I just measured the bore size on, which are OEM style of course (8$ per gasket via Rockauto sale recently), and they come out to 96mm. So if the liner itself isn't that wide, which I'm not sure of the actual wall thickness of the liner myself, then there's little to no fire ring of the head gasket actually on top of it to stop it from moving. Even if there is, the fire rings look pretty weak on these composites and could still get beat up easily.
MLS gaskets are superior to composites in my opinion. They're definitely not gonna blow out at the back water passage and crap like composites always do at least. MLS are usually a little more picky when it comes to having a nice flat prepped surface compared to composites though.
I think Extinct presented this information first a while back, can't remember exactly before I looked into it myself.
I prefer studs over bolts, but that's just me. I hate torque to angle bolts the most.
I'm an LS engine guy (in my other vehicles, not in my disco. yet.) and we don't have to deal with BS like slipped liners, nor have I done it to my Rover (yet), so I guess just take this information as more of theory from me as I haven't put it into practice. With that being said, if you have a cracked block between sleeve and water jacket, nothing is going to fix it except a major rebuild or new engine, and at that point you would be better off going with an LS swap for many reasons, cost and reliability being the main ones.
The 4.0 and 4.6 blocks, according to spec, use a 94mm bore. The liners also apparently sit on a lip at the bottom, preventing them from moving downward into block, but nothing preventing them from moving up to the top besides the head/gasket.
In theory, if the liner is already fully seated against the lip at the bottom, and you use a 94mm Cometic MLS gasket, it will prevent the liner from moving completely.
I have some Fel-Pro composite gaskets I just measured the bore size on, which are OEM style of course (8$ per gasket via Rockauto sale recently), and they come out to 96mm. So if the liner itself isn't that wide, which I'm not sure of the actual wall thickness of the liner myself, then there's little to no fire ring of the head gasket actually on top of it to stop it from moving. Even if there is, the fire rings look pretty weak on these composites and could still get beat up easily.
MLS gaskets are superior to composites in my opinion. They're definitely not gonna blow out at the back water passage and crap like composites always do at least. MLS are usually a little more picky when it comes to having a nice flat prepped surface compared to composites though.
I think Extinct presented this information first a while back, can't remember exactly before I looked into it myself.
I prefer studs over bolts, but that's just me. I hate torque to angle bolts the most.
I'm an LS engine guy (in my other vehicles, not in my disco. yet.) and we don't have to deal with BS like slipped liners, nor have I done it to my Rover (yet), so I guess just take this information as more of theory from me as I haven't put it into practice. With that being said, if you have a cracked block between sleeve and water jacket, nothing is going to fix it except a major rebuild or new engine, and at that point you would be better off going with an LS swap for many reasons, cost and reliability being the main ones.
Not Land Rover specific but the details should be relevant. One concern I would have is the need for the surfaces to be very flat and smooth. I get that if you have the heads machined that would be possible for that surface but if the block remains in the car for the job I don't know of that could be checked or done to assure the surface is smooth enough. I notice on a spare block I have the old composite gaskets leave a pattern in the deck that would probably need to be polished or machined out, and kept flat.
#17
01-10-2022 | 12:08 PM
Camel Trophy
Joined: Sep 2017
Posts: 3,545
Likes: 1,184
From: Mission BC Canada
@dswilly In my experience the block rarely needs work beyond cleaning, it is painful but doable with gasket cleaner and soft abrasives like plastic scrubbers and scrappers. Mine took about 5 hours to get sorted out when I did my head gaskets. There is micro-polishing paste used for acrylic hot tubs that works great to put a polish on the top of the block, it is just a lot of work by hand.
#18
01-10-2022 | 01:19 PM
Rock Crawling
Joined: Jan 2011
Posts: 499
Likes: 141
@dswilly In my experience the block rarely needs work beyond cleaning, it is painful but doable with gasket cleaner and soft abrasives like plastic scrubbers and scrappers. Mine took about 5 hours to get sorted out when I did my head gaskets. There is micro-polishing paste used for acrylic hot tubs that works great to put a polish on the top of the block, it is just a lot of work by hand.
Straight – Both sealing surfaces must be flat to allow for a proper seal. Fel-Pro’s recommended maximum limit for flatness is .004-inch lengthwise and .002-inch width for V-8 engines. A maximum out-of-flat of .001-inch in any 3-inch diameter should not be exceeded.Smooth – Also called surface roughness. How smooth the surface is will dictate how well the head gasket can seal. There are two measurements of surface roughness (with all values in micro-inch – µin) Ra is the average roughness height, and Rz, is the average peak-to-valley roughness height.
Composite gaskets will typically like surfaces ranging from 60-80 Ra (360-480 Rz), as surfaces much rougher than this will limit gasket conformance. MLS head gaskets favor smoother finishes and only a maximum roughness of 30-80 Ra (180-480Rz) are recommended. Check with your gasket’s manufacturer for specifics, but when it comes to MLS gaskets, smoother is always better.
Clean – When micro-inches matter, any foreign material can hinder a quality end result. That’s why MLS head gaskets are designed to be installed dry. As mentioned, they already have a coating on the external surfaces of the gasket to promote sealing to the mating surfaces of both head and block. While MLS gaskets from various manufacturers may differ from one another, all gasket manufacturers agree that no other sealer is necessary or should be used with MLS gaskets.
I did notice on my spare block the deck surface is very smooth and almost looks polished. There are no machining marks at all, just the gasket residue and etching mentioned. So maybe the Rover deck is smooth enough for MLS gaskets stock if kept flat enough.
#19
01-10-2022 | 01:41 PM
Camel Trophy
Joined: Sep 2017
Posts: 3,545
Likes: 1,184
From: Mission BC Canada
You can check the block for true, both my spare and current were both good as far a true went. Used a straight piece of aluminum a very good set of feeler gauges and a light to check. The light lets you easily see if there are any obvious gaps
Last edited by Richard Gallant; 01-10-2022 at 01:44 PM.
#20
01-10-2022 | 06:06 PM
Rock Crawling
Joined: Jun 2016
Posts: 461
Likes: 185
Guys I know this conversation has been had multiple times over the years. I have looked at many threads going through the ins and outs of working on these motors. Recently i have about a Disco with a blown head gasket. The guy got in the middle of changing the gaskets out and gave up due to other unforeseen issues. With that being said i bought it from him and i am looking into what do to make a good long term vehicle for excursions with my family. The options i was looking at was getting the heads surfaced, buying some good head gaskets (cometic), ARP head studs and putting it back together. Another option i had looked into was buying the ACE kit and putting a 5.3 in it. I am just wanting to know some recent opinions on that kit and that swap. I would also like to know if installing the head studs, surfacing and a good gasket would be an adequate repair. I read somewhere that the cometic gaskets can keep the sleeves from moving? I am not sure how accurate that is.
Thanks ahead of time
Thanks ahead of time
I wouldn’t go back to dealing with the constant leaks and little issues with Rover V8. The 4.0 is a bit less temperamental than the 4.6. Neither compare to the 5.3, which once running, has basically only required oil changes.