Liner failures in Land Rover V8 engines ? what's happening?

[robisonservice]

Land Rover Discovery II overheating engine failure is getting more and more common around here. The "traditional explanation" is that the liners shift within the block and somehow combustion gases get into the coolant. In the early days I know that was true because I saw 1990s engines where the liners dropped slightly into the block. However, LR supposedly fixed that issue, yet the failures continued. In fact, the engines in the last Discovery II models seem to fail at a higher rate than the 1990s models.

I have also seen liner movement blamed for engine noises. Is that accurate?

We recently cut a 2003 Land Rover Discovery engine in half to determine why it failed from overheating. Are the "slipped liners" real or not? I have the writeup and pictures on my car blog at robisonservice.blogspot

 

[ptschram]

Hey John!

Any chance I could get you to cut a chunk out of that block so I could show clients what the liner's relationship with the block looks like? I'm hesitant to cut one up, but if you've already done it, I wouldn't be destroying a potentially rebuildable (new liners) block.

So far, we're running about 70% of overheating DIIs being able to be returned to service with just resurfacing/valve jobs and gaskets.

Some have reported noises from the counterweights hitting the bottom of the liner. So far, I haven't seen one do this yet.

Hope all is well.

PT

 

[R_Lefebvre]

Interesting stuff. How far down does the head bolt protrude into the block? That crack seems to be not far enough down to line up with where I might expect a failure as you're suggesting: the bottom threads of the bolt, where the aluminum is under the greatest tension.

http://2.bp.blogspot.com/_lmvhkBcrmsY/S8uvBSeTLVI/AAAAAAAACDc/tES-JBp9CR4/s1600/rover-1489.jpg

Isn't this picture showing pretty significant casting porosity?

 

[JohnB]

Looking at that crack one wonders if the crack came from the smack-down dealers who replace head gaskets on warranty pay.

I'm sure if they didn't clean the threads out this could happen.

 

[robertf]

good stuff John. So it sounds like tophats are the solution to the paranoia

Thats where my second 3.9 failed. It was a dealer replaced 3.9.

 

[2FUELS]

Would replacing the head bolts with studs be an alternative...(he said thinking out loud)

 

[robertf]

maybe, maybe not. theres pressure from the pressed in liner, tension from the bolt, and cyclic loads all done on a material that will eventually fail from fatigue. living with the crack is probably the best solution.

maybe converting the blocks to a semi wet liner is the solution.

 

[mgreenspan]

How hot do the bolts get? Could them expanding (from heat) result somehow in the crack? I know that jacks for our leading edge flaps can get stuck if we have bleed air issues and leaks putting heat on them causing the flaps to get stuck in position. Not sure if the jack screws crack anything, but they can expand and prevent it from moving.

 

[ptschram]

How hot do the bolts get? Could them expanding (from heat) result somehow in the crack? I know that jacks for our leading edge flaps can get stuck if we have bleed air issues and leaks putting heat on them causing the flaps to get stuck in position. Not sure if the jack screws crack anything, but they can expand and prevent it from moving.

The coefficient of expansion due to heat for the aluminium head is greater than the expansion of the steel bolts, thus one would expect greater clamping force at op temps than the opposite.

I don't see studs doing a whole lot as we don't seem to see the engine failures in the Motronics Range Rovers, thus supporting my contention that it's the DII cooling system and worthless temp gauge.

 

[ozscott]

Arrgghh...the great way to preserve a D2 engine...regular Penrite oil, regular red coolant and rad checks (and flush when required), keeping and eye on hoses, scan gauge for more accurate readings of temp AND low water engine saver stuck in where the bleed screw is in the top radiator hose....very nice combo that has served me well so far. I reckon if I had a 4.0 D2 that got (properly - which isnt hard with alloy) cooked I would just R.I.P. it out of the bay and do a changover for a 4.6 block and re-use the head gear after crack testing and doing some porting and polishing, new valves gear and a slightly mild cam, full balance including the harmonic balancer and away we go....

Cheers

 

[gmookher]

just swap out the crappy fan clutches at 70k, and keep fresh dexcool current

 

[JohnB]

thus supporting my contention that it's the DII cooling system and worthless temp gauge.

I'm still loving my inline thermostat on my D2. My temps went from 210 down to 190 idling or driving. We'll see how it works this summer. When I deleted the OE by-pass thermostat I cut it open to look at it. What a marvel of comeplete crap.

 

[gmookher]

I'm still loving my inline thermostat on my D2. My temps went from 210 down to 190 idling or driving. We'll see how it works this summer. When I deleted the OE by-pass thermostat I cut it open to look at it. What a marvel of comeplete crap.

is there a post where you have this mod written up??

thanks

 

[JohnB]

http://www.discoweb.org/forums/showthread.php?t=64366

 

[gmookher]

thanks!

 

[jymmiejamz]

I don't maintenance has anything to do with it, I think the tooling to make the blocks was probably worn out, but that's just my .02.

 

[robertf]

Hey John were you able to pull the liner out in one piece? I'd like to know the liner OD and the aluminum cylinder bore ID if you've got them.

 

[robertofollia]

Please do stick this post as well. There's so much wisdom concentrate.

Best regards and thank you

Robert

 

[jymmiejamz]

I posted this in the thread in the Range Rover section...

Another tech at our dealership had the liner machined out of the block I gave him out of my truck (never overheated AFAIK). We then pressurized the block and could see an obvious crack in it. He had the machine shop weld up the crack and press in a new liner, but he has yet to put it in a vehicle.

The reason it may seem like a liner issue is because when you pressurize the block (with the liner in) it will leak out around the top or bottom edge of the liner. The actual problem is the block behind the liner. Also, it is almost always cyl #4,6,3, or 5, but we've also seen #8.

 

[Dalton305]

very nice post, thanks for sharing.