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Cracked Block 3.9!


cosbros
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My '92 Vogue has the dreaded crcked block and is now draining the local resevoirs at an alarming rate! Have considered replacing with remanufactured engine from Turners, ACR etc but then noticed the 2.8 TGV diesel from M&D!

Has anyone got experience of this engine?

I am looking to keep the Range for 5-6 years at least and want the best reliability and economy possible.

If I do go down this route I will have a 6 month old LPG kit for sale!!!

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Stick a 200/300 TDI in it,at that age of car its the best option in terms of ease of fit,parts availability,reliability and economy,just buy a rusted out mot failed Disco and you have 99% of what you need.Plus you can sell the rest of the bits,diffs etc to get some of your money back.

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You can pick up a 3.9 efi for little money now, some are good low milegae units, sell off the bits you don't need, or keep assapres.

Dependant on how good a condition your is, and as to how long you wnat to keep it even a new short engine can be got for decent money ?

Nige

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There's a whole vehicle in the classifieds for £350, failing that I have a mate who deals in RR bits can sell you a good 3.5, 3.9, 4.2 or 4.6 depending on your budget. TDi conversion would be big work and if it's an auto the parts are like rocking horse poo.

Edited to add: You've got LPG kit already so will get similar or better pence/mile than a TDi and that's before you count the cost/hassle of buying one and doing the work. The V8 is so cheap to maintain/replace compared to TDi (and has anyone else noticed the gradual increase in TDi timing belt/head gasket failures as they start to get on a bit?) I wouldn't bother.

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Car is in exceptional condition and I am only the second owner! Am looking to keep it going as long as possible and don't want to keep replacing engines! How many V8s do crack, anyone know? Mine went at 102000!

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Any of the 94mm bore block v8's will do it,stick to a 3.5 if you want a reliable one.Better still put a sequential Lpg kit on it,run it closed loop with oxygen sensors.

Or you you could do the TDI thing,have total reliability,(with correct maintenance)fuel from any garage,no problems with insurance companies wanting carp LPGA certificates and best of all it will be worth loads more when you do want to sell it.

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As I understand it the 3.9's are pretty reliable, it's only the weaker mixtures run by the later lumps in the quest to pass emissions standards that caused the problems with liners / cracking. And, as I said, new lumps start at around £250 for a 3.9 or less for a 3.5.

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(and has anyone else noticed the gradual increase in TDi timing belt/head gasket failures as they start to get on a bit?)

This fact is just sooooooo often ignored, when the seemingly age old Tdi vs V8 argument crops up, they never ever state that the V8 was born in the 1950's not the late 1980's.

In a like for like diesel argument - it would be the 2.25ltr Diesel vs the 3.5V8 - oh dear :lol:

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As I understand it the 3.9's are pretty reliable, it's only the weaker mixtures run by the later lumps in the quest to pass emissions standards that caused the problems with liners / cracking. And, as I said, new lumps start at around £250 for a 3.9 or less for a 3.5.
If you want a V8 for little money then stick to a 3.5,I see far to many 94mm V8's with coolant loss,rusted in spark plugs and rock hard hoses.It is alot of work to strip and rebuild a V8 properly with stepped liners - which is now the only safe way to do it.I dont think the later engines are any worse because of their emissions parameters.They run with more accurate control,having closed loop control and twin knock sensors - plus accurate ignition rather than a hit or miss distributor.

Fit the 14 cux injection system to the 3.5 engine and thats about as good as it gets with standard Rover bits - esp if you use it closed loop.

Diy - TDI any day.

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You have a V8 with parts and ancillaries that you have maintained and know the history of. As Hybrid said before, you can buy a shiny new/recon short (or long) linered block which you can attach your parts to for similar or less money, by the time you have mucked around, than a second hand tdi that you will know next to nothing about.

Just look at all the postings on here with regard to swapping (V8 to tdi and visa versa) engines about :blush:, which although simple in theory, seem to often end up being an ocean going PITA.

My vote - Stick to what you know works.

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  • 3 weeks later...

I agree stick with the V8. I've several 3.9s and had no problem with the so-called porous block syndrome... it does happen on 4.2s a bit and I've seen several get swapped at around 100,000 miles. It is caused in part by the emisions driven engine mapping and in part by the auto box trying to stay in too high a gear, making the engine slog and heating the top of the cylinder up too much.

Twin knock sensors though :huh: , not on a Classic

Many of the later engines don't have liners though, they are 'nicosil' lined or whatever it is.

My big problem is burning out exhaust valves, but that's another story.

No, stick with a V8. Look after it and change down a bit more often. When I'm towing with the LSE I'll pull the auto into 3rd to make the engine spin a bit more, it keep the temp down a little and doesn't stress the engine as much.

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I agree stick with the V8. I've several 3.9s and had no problem with the so-called porous block syndrome... it does happen on 4.2s a bit and I've seen several get swapped at around 100,000 miles. It is caused in part by the emisions driven engine mapping and in part by the auto box trying to stay in too high a gear, making the engine slog and heating the top of the cylinder up too much.

Twin knock sensors though :huh: , not on a Classic

Many of the later engines don't have liners though, they are 'nicosil' lined or whatever it is.

My big problem is burning out exhaust valves, but that's another story.

No, stick with a V8. Look after it and change down a bit more often. When I'm towing with the LSE I'll pull the auto into 3rd to make the engine spin a bit more, it keep the temp down a little and doesn't stress the engine as much.

The knock sensors are fitted to the later 94mm engines in Lp RR's from 95 - 02 with Gems or Bosch injection.I think poor radiator flow in the later auto classics has more to do with cracked blocks and overheating.The oil cooler in the end of the rad restricts flow badly.As for the story about lean mixtures from the fuel mapping of the ECU,thats rubbish - ever watched oxygen sensors switching on a scope whilst driving one ? They do exactly what you would hope they would,switch nicely while cruising,and immediately go rich when you put your foot down.Which is something that very few single point LPG equipped cars ever manage.THAT is a good recipe for poor mixture distribution and overheating.

Trouble is you still cant get past the fact that the 87.5mm bore blocks never did it,(cracked) and will tolerate all manner of abuse and carry on.

For a long term V8,use a 3.5 with 14Cux injection,(as fitted to disco's) and run it closed loop - without cats if you dont have to.Put LPG on it if you want,a port injected one preferably.Then you can thrash it,abuse it,do what you like with it and it will keep going.

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you've got an LPG kit and a perfecally useable setup at the moment- you won't get any better economy on Diesel compared to lpg and if you get a top hat block then there won't be much in it for reliability.

If you are up to it yourself you could build the block yourself from a turners top hat jobby- you can pick up cranks and rods for not a lot of acsh nowadays and you could end up with a very powerful, reliable engine for at loss less hassle then switcing to a tdi.

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  • 3 weeks later...

Stick an oil burner in it... then i can buy your LPG kit so that i never lose the glorious power, sound and flexibility of my V8!

:lol::lol::lol::lol:

My last V8 went porous at 160,000 miles, didn't think about putting a diesel in, just tried to find the best 3.9 i could.

With hindsight, i should have saved up a bit and got a 4.6. Hey ho.

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