3.9 liner problems

[DaveEFI]

To try and help me decide on things, just how common are liner problems on a 3.9 block? Apart from plain wear, obviously. More common than on a 3.5?

[kiwicar]

Hi Dave
From the research I have done in the past across many threads on many forums there are two main reasons for water leaks around liners, firstly what could be termed age related, where the block has, for one reason or another, usually not enough anti freeze or poor semi dry storage then reuse of the engine the block has become filled with crud and hot spots have developed that have cracked the block at the deck. Often to a bolt hole and the liner has become loose, this happens in older engines, 100k plus miles, usually 3.9s. there appear also to be some cases where the QC was so bad that engines went out the door withthe liners not properly seated, these ones seem to be on the first of the 4.2s in RR classic long wheel base (I have found 2 4.2s like this on forums in the pastand considering they did not make very many......). I will say the QC related problems seem to be related 3.9s and 4.2s and this is what kills these blocks.
The cracking behind the liner resulting in the liner dropping problem, from what I have found seems to me to be a fault related almost entirly to the 4.0/4.6 block. In this case I think after the very poor reputaton of the 4.2 for reliability (the nose falling off the crank, warped heads and snapping rods) I think the QC roblems were mostly sorted. I also think the new/ refurbished production line for the new block meant the liners were being seated properlyin the first place so the later problem was being seen first. This was the time rover had been sold, that is where the money came for the 4.6/4.0 blocks and the new owners were trying to sell off landrover to get back some of the investment money.
I have seen posts with problems relating to the more unusual blocks like the 3.5 cross bolt and the cross bolted 3.9 intermediate blocks, but I think these relate to use in that the owners were pushng the outputs to ponts where the rover is just not strong enough to hold together.
Generally the middle run 3.5 block seems to be liner problem free, they were made before the issues of QC andthe early 3.9s with the extra webbing were pretty good it was on the 3.9/4.2 blocks where the casting/machineing lines were old and worn out, that liner/QC problems started remember the 3.9s were from the time the government were trying to sell off rover to the lowest bidder and did not want to spend any money on it and rover had spent a load ofmoney on the iceberg engine thatnever made it to ptoduction and so they used upall the bits from that project into RR production engines, and dumped a load of the bits on TVR.
Also the later 3.5 blocks were strengthened for the Range rover but were only expected to make about 140 bhp so the stresses on them were much less and had non overdrive autos with non lock up converters, or ran low geared 4 speed manuals, though some had O/D units fitted they did end up with a very pedestrian shift that did not lend itself to giving the engine a good thrashing! I think here as you imply with the 3.5 the issue is old age of the blocks and lack of maintenence/anti freeze causing block problems.
Avoid the very early P5/P6 and the 101fc and stage 1 v8 blocks they are very week around the valley area and had a reputation of falling in half down the middle if stuckin a heavy vehicle/ tuned and reved, these were still the old stock that came over from Buick when rover bought the design and date from '61/'62 and were very exotic casting technology for GM at the time!
Best regards and a happy new year
Mike

[Mark]

I had a 3.9 where a liner had slipped own into the block by a few thou.

Head gasket then leaked

[DEVONMAN]

I had a 4.2 lump (These use a 3.9 block) that leaked from behind the liner into the sump. This engine was fine for two years and developed the problem after it had overheated in traffic twice.

I have seen a TVR 5.0 (These use a 3.9 block ) with a cracked liner.
I don't know the history.

I have seen a 4.6 with a slipped liner. Don't know the history.

The information on the net re this subject is massive and confusing. But of course only the bad cases are reported and this is a small percentage of the rover v8 numbers.
I believe the problem is related to temperature and the different expansion rates of the liner and the block. I have read about an increased number of cases where the vehicle is used north of the artic circle (say -20 degrees ) and the cold to hot differential is therefore greater. It was suggested that when cold, the ali block would contract sufficiently to crack due to the liner resisting this contraction. All this depends on the degree of interference fit at the factory and would therefore is QC matter. Probably why some lumps are good and some go bad.

I have read also about the top hose problem on the 4.6 range rovers where after a burst hose had occurred at speed the engine went bad.

If it was me I would be looking for a good runner with reliable history and then make sure it never overheats.

Regards Denis

[SimpleSimon]

I strongly believe a lot of the so called cracked block/liner issues are created by overheating i.e letting the coolant run low, or at least coolant dropping below cylinder head threshold, most of the TVR related ones I have heard of are anyway or some kind of boiling up history many TVR owners consider regular maintenance sticking it into an indy once a year with out lifting the bonnet in between so hardly surprising really that the levels dropping go unnoticed obviously the hotter running temps of the late RR's with the 4.0/4.6 & leaner burn ever tightening emissions etc and lugging that big old body around are different conditions for the problem though along with worse quality control near the end of production .......... maybe

[ChrisJC]

The 4.6 block cracked in my Range Rover at about 100K miles. The engine had never overheated. I have no idea what triggered it.

I can recall the days when the 3.9 was a current engine, and there was talk then of 'porous blocks', before the actual cause was understood (or at least, was in the public domain).

So I would treat any 3.9 with caution.

Chris.

[DaveEFI]

Are there any tests I can do myself on a bare 3.9 cylinder block? The top of the liners appear to be in line with the block face - I assume not all would slip uniformly?

[DaveEFI]

The 4.6 block cracked in my Range Rover at about 100K miles. The engine had never overheated. I have no idea what triggered it.

I can recall the days when the 3.9 was a current engine, and there was talk then of 'porous blocks', before the actual cause was understood (or at least, was in the public domain).

So I would treat any 3.9 with caution.

Chris.

I know things based on personal experience ain't definitive, but I do know personally of a few who've had problems with a 4.6 - but not of any on a 3.9.
I suppose it might depend on when they were made - tooling etc getting worn out. Most of the 3.9s I know of would be fairly early engines.

[ChrisJC]

The 'word on the street' is that the 4.6 was the most prone because of the higher power output and the heavier vehicle in which the engine sat. So the internal stresses were higher.

It is entirely possible to check a block:

by using my test plates.

Chris.

[sowen]

Are there any tests I can do myself on a bare 3.9 cylinder block? The top of the liners appear to be in line with the block face - I assume not all would slip uniformly?

Like Chris I made my own pressure testing kit, I used some 10mm steel plates cut and drilled to bolt onto the block over the water jacket and plugged 100psi in. It showed up a few faults on my 4.0 block which I intend to try some SteelSeal treatment first.

There was quite an involved discussion on my SD1 thread on the SD1 forum about the quality and grading of the 4.0 and 4.6 blocks, mostly attributed to worn tooling and quality control issues, interesting reading.

[DaviesDJ]

My mate Richard re-lines all wider bore blocks and over 50% will have cracks or porosity. This is done on all blocks as a matter of course. It was more common on 4.0/4.6 as they run far hotter combustion temperatures to keep emissions satisfactory

[MikB]

My 3.9 RRC cracked after only 60.000 miles - bought a relinered block at Turners Eng., and never looked back

[Muscle-Manta]

With regard to the 4.0 and 4.6 engines. They were graded and colour coded. Take a look at the last post on page 5..... on the thread in the link. All 4.6 engines were red grade blocks. At least the ones manufactured by Mitchell Cotts.

http://www.v8forum.co.uk/forum/viewtopi ... c&start=60