Isuzu 3.9 longevity?

[Clark]

Hi guys,

I'm keen to get a County, and am aware of one that's available with the Isuzu 3.9 diesel in it, for what seems a reasonable price.

The particular vehicle has done around 410000km's though.. I realise this is a diesel and they last ages, but what kind of life can I expect from one of these engines before they need a major overhaul? What tends to fail? Would this many k's be seen as an engine getting tired and soon needing major work?
(I haven't seen the car yet)

In addition to the engine, what else should I be looking at? Seems like a lot of k's for the gearbox, suspension, etc to go through?

Or am I being too paranoid, and these old girls last forever? I'm happy to work on the car, and not expecting something pristine. But nor do I want to purchase it and find I'm up for a gearbox and engine overhaul straight away..

Thanks for the help.

[130man]

Hi, Clark, the 3.9 Isuzu engine is well regarded as an excellent long term motor.I owned one for 15 years in an '85 County and it didn't miss a beat.Originally designed for a truck, it is understressed driving a 110.Excellent torque at low revs but it does not like to rev out and I found it somewhat frustrating at highway speeds.Mine had the LT95 4 speed g/box and clearly would have benefited from another gear.Some people have the LT85 [Santana] box. Superb in off road work.Hardly ever used first as second low would master anything.It all hinges on the maintainence history.Well maintained, you should expect at least 600,000 kms and more if well looked after.They do give the transmission some strain as the big power pulses of the 4 cylinders hammer the bearings more than sixes might do.I had to repair my t/box which had wear marks the mechanic said only occurred in the Isuzu engined vehicles.Also, I found mine fairly noisy and placed extra sound insulation in the cabin and engine bay.Hoope this is useful.Cheers, 130man.

[DRanged]

If properly serviced Isuzu claim a cycle life of almost 1million km's. Bit hard to know the full history of an engine if you have'nt owned it from new though.

Justin

[justinc]

Can't hurt it...
Can't seem to wear it out...
Can't live without it....

These things with a good service history will live forever, The rest of the 110 will have returned to its natural state before the engine wears out.
I would check very carefully the transfer case for excessive noise and backlash, the 4 spd for ease of gear selection and make sure it doesent hop out of gear or out of high range on the over run or under load.
The diffs are pretty strong, the rear is almost set and forget, the front can break inner axles as these are coarse spline, the outers fine spline and the CV's almost indestructable unless run out of oil(!).
I would love a '85 110, finding one is very hard indeed. If you are near to a decent LR enthusiast staffed workshop, get a FULL appraisal first. It might be cheap to buy, but can be big$$$ if you get a dud.

Good luck.

JC

[County3.9]

JC is spot on (of course). Rust in the doors and firewalls are biggest problem for me. I can fix most mechanical bits but panel work is a problem without specialist knowledge.

[rar110]

On my previous 86 Isuzu county that had about 400k, it needed front crown wheel and pinion, spline on main shaft worn, rear seal leak, rear diff seal leak, engine shut down replaced, ignition switch replaced, transfer box was looking doubtful, rear cross member and doors suffered rust, fuel tank leak, rear drive shaft worn, front cvs were starting to get a clicking noise, the lift pump died.

The motor was great, just loud. That didn't stop me buy another.

I have had both 4 and 5 speed. The 5 speed from memory was a little better on the highway. Both would only do about 110km/hr.

[incisor]

anecdotal evidence suggests the motors will last much longer than your hearing and spine if regularly maintained.. ;):D:eek:

[isuzurover]

What others have said.

Mine has 330000km and hasn't missed a beat except for needing a gearbox rebuild (LT85) and a few other minor bits. The engine doesn't use any oil between services.

The only ones I have heard of with blown engines have been driven without water and cooked. A mate bought one with 200k km on the clock with just that problem. It cost him about $4k to pay a mechanic to do a full rebuild (pistons, liners, bearings, etc, etc.).

[Bigbjorn]

I have had both 4 and 5 speed. The 5 speed from memory was a little better on the highway. Both would only do about 110km/hr.

My five speed tops out at 125kph and cruises quite happily in o/d 5th at 110-120. Must have been something wrong with yours. Theoretical top speed at governed 3200rpm is 163kph but there is not enough power available to reach this speed. Cruising at 2000-2200rpm is quite comfortable and economical, up to 30 miles per gallon.

[EchiDna]

tyre diameter perhaps?

haven't had mine above 115, but then I haven't tried either (turboed, santana box, 4.11 transfer case and 35's)

mine is on a probable 380k, going great...

[kaa45]

BUY IT!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! :D
We need more Isuzu owners on here. :p

[rar110]

Your probably right Brian. It had a few problems. On one trip I did wind it out to 115km/h but it was screaming. I don't know - I was running 750 16s. Another on this forum has had his upto 140km/h.

The difference btw lt 85 and 95 on the final drive ratio is negligible isn't it?

[isuzurover]

Your probably right Brian. It had a few problems. On one trip I did wind it out to 115km/h but it was screaming. I don't know - I was running 750 16s. Another on this forum has had his upto 140km/h.

The difference btw lt 85 and 95 on the final drive ratio is negligible isn't it?

Yes - almost no difference - High range in the t-case is 0.998:1 (LT95) and 1.003:1 (LT85). 2nd-4th are basically the same ratio in an LT95 and LT85.

My (5-speed) will do 130km/h in 3rd gear at redline. A mates 4-speed will do the same. Mine will sit happily at 120km/h in 5th if there is no headwind.

[Bigbjorn]

Yes - almost no difference - High range in the t-case is 0.998:1 (LT95) and 1.003:1 (LT85). 2nd-4th are basically the same ratio in an LT95 and LT85.

My (5-speed) will do 130km/h in 3rd gear at redline. A mates 4-speed will do the same. Mine will sit happily at 120km/h in 5th if there is no headwind.

Overall gear ratio with 3.55 diffs, LT95 four speed, LR230T transfer is 3.52:1 in fourth.
With 3.55 diffs, LT85 o/d fivespeed, LR230T transfer is 2.82:1

Formula for road speed against engine speed is (60 x rpm) / (overall gear ratio x tyre revs. per kilometer).

Tyre revs per kilo. are :- 7.50 x 16 - 408.5; 31 x 10.5 x 15 - 417.4.

In round figures my five speed County on 31's is revving at 2000 at just over 100k's, 2200 at 110, and 2400at 120. 100-110k's cruising speed is right on the point of maximum torque rise, the steepest part of the torque curve and just over the speed (1900) of peak torque.

If anyone would like a copy of a gear split chart for a County, PM me with your postal address.

[rovercare]

3.54:1 not 3.55:1 differentials:angel:

[JDNSW]

And while we are splitting hairs, the LT95 is a combined four speed gearbox and transfer case, does not use a LT230T transfer case, although the works are very similar.

John

[Bigbjorn]

3.54:1 not 3.55:1 differentials:angel:

Perhaps we should use crownwheel teeth/ pinion teeth to satisfy the pedants? 37/9 = 4.1111111111 for example or 39/11 = 3.54545454 et so vide.

The difference is which way you take the nearest decimal.

[Bigbjorn]

And while we are splitting hairs, the LT95 is a combined four speed gearbox and transfer case, does not use a LT230T transfer case, although the works are very similar.

John

My Australian owners manual calls the 4 speed's an LR 230T transfer case, whilst my (English) factory workshop manual calls it an LT95 "transfer box". The 5 speed LT85 is described as having an LR230T in Australia and an
LT230T in England?

The truth shall set you free?

[rovercare]

Thank you:)

[isuzurover]

My Australian owners manual calls the 4 speed's an LR 230T transfer case, whilst my (English) factory workshop manual calls it an LT95 "transfer box". The 5 speed LT85 is described as having an LR230T in Australia and an
LT230T in England?

The truth shall set you free?

Really? What year is your owner's manual? I am sure mine says LT230 - will have to check when I get home...

[Larns]

I rebuilt an Isuzu last year (mine:D) and it was an effort to find rebuild parts for them. Isuzu's official responce to me was that if it was bad enough that the whole engine required to be recoed then get a different one. They only sell ring kits for individual cylinders, because it's so rare for the lot to require rebuilding. They said that the branch in Melb. recently had one in for a rebuild, it had done over a million K's!!!!!!!!! an they reckon that they put a seal/gasket set through it, new bearings and recoed the pump an injectors. That's it, it's previous history was- serviced every 10k and had had the injectors done at 480k and 720k mark.
They are an exceptional engine, if you regulary service them they will never let you down. An if your lucky enough to get the turboed version then they have as much torque as a small block chev, they just lack the HP to match:D.

Those figures for 5 gear crusin are interesting, my LT95 has me doing about 2800rpm at 100 and 2200rpm at 80km/h, and it's supposed to have a 1:1 high range. I'm a bit dubious about the ratios and gearing that the box has as it came out of a range rover, it feels different to drive ,gearing wise, than all the other Isuzu LT95 110's that I've driven.
I've just finished rebuilding the R380 to go behind the old girl. The LT230 that I've got has a 1:1 high ratio so I'm hoping to be around that 2200rpm mark at 100km/h that you guys have.

:twobeers:

[justinc]

* sigh* Just went for a drive in mine, much better after the gearing change.

I've heard the 1,000,000km claims also, and looking at it, I'll be taking this engine with me when and if I change vehicles!

Such a joy to have such a lazy, torquey and RELIABLE engine under the right foot:D:D

I love my Isuzu:):):):)

JC

[isuzurover]

My Australian owners manual calls the 4 speed's an LR 230T transfer case, whilst my (English) factory workshop manual calls it an LT95 "transfer box". The 5 speed LT85 is described as having an LR230T in Australia and an
LT230T in England?

The truth shall set you free?

Checked my manual over the weekend. My Australian manual lists 2 t-cases: LT95 (4-speed) and LR230T (5-speed). Strange that they got one right but not the other.

Other interesting thing is they list about 3 different low range ratios for the LT230 - they claim the 3.9D county (5-speed) has a low range of 3.198(?). Surely this is wrong? I always understood that ALL LT230s came from the factory with 3.3:1, and that low range was unafected by changing the high range ratio.