Thread: The 85 Classic

Originally Posted by Judo

Upsized radiator and intercooler and the TDI could be tuned into the "acceptable" range....

I just looked at the specs. 19.9 seconds to 100km/h for the 300tdi automatic soft-dash. 12 seconds for the V8 auto.

12 seconds and 20.2 litres/100km for the V8 (urban cycle)
vs
20 seconds and 9.8 litres/100km for the 300tdi auto. (urban cycle)

And the guy who has it wants a V8 rangie instead. I'm sure we can come to some arrangement eventually.

The new head gasket for the 4BD1T arrived this week. We'll see how much spare time the weekend brings.

I have had an industrious weekend. I started the head gasket replacement at 10am saturday and was done by 12 noon sunday. About 6 hours total work in that time.

Things got scary. But first some background.
The engine was rebuilt in December 2005 in-situ using genuine gaskets, big end bearing shells and piston rings.
Aftermarket new chrome liners were used from an incomplete 6BD1 rebuild kit (swapped for beer), new aftermarket pistons were used which are Alfin type (reinforced top ring-land) and indistinguishable by eye from the genuine pistons I have from many moons ago.

Since then it has done 46,730km, the first ~13,000km in a state of tune not passing 600C EGT. The remaining ranging from backing off continually to stay under 750C to finally being set to hit 750C under sustained load.
EGT and boost gauges have been fitted the entire time. It has seen 900C several times due to inattention and other factors.

11,000km ago I fitted a provent air/oil seperator with the intent of removing virtually all the oil present in the breather circuit back to the turbo.
Instead the opposite occured. The provent sucked oil out of the sump and fed it into the intake.
This occured in sufficient volumes to cause the engine to run on it's own oil, producing large volumes of smoke (enough to hide a petrol station), sustaining the rpm at ~2,500 and causing serious hammering vibration. This occured many times when I was driving but also while my wife was driving along.
In the 2 months and 1640km I had the provent fitted as per the manufacturers instructions approximately 8 litres of oil was consumed by the engine in this manner.
The engine had not used oil before the provent fitment or since it was modified.
The engine had also not lost water before the provent was fitted.

I removed the provent and made several modifications to allow it to work as it should have:
http://www.aulro.com/afvb/isuzu-land...on-dr-ben.html

These modifications solve the oil feeding problems completely. But I was still left with engine damage of at least a blown head-gasket.
After 2 years and ~12,000km of adding water to the radiator I finally had a chance to deal with it.

One genuine Isuzu gasket (8-94145839-1) and into it.

First progress photo. Head is off. The gasket is stuck to the head, the block surface is clean and there's a scary wear mark showing on cylinder #3 (circled in red).



This is harder to see from above, but it's a chunk missing that has worn through the chrome coating into the steel beyond. But is now surprisingly smooth. I wasn't pulling the piston to check further.





Peeling the gasket off the head shows exactly where the problem lies. Cylinder #3 is the one that gets the majority of any debris (or litres of oil) coming in the intake (prior experience with dust etc). This is showing blow-outs almost the entire way around.
Cylinder #2 is second worst.
But none have escaped unscathed. The gasket has blown on all cylinders.



Head as peeled:



Surprisingly all the bolts visually checked out fine and soo did the head once cleaned up. Note the pock-marks from debris with a failed air-cleaner many years ago. I still have the pistons from that rebuild, a stone is embedded into one.



Lots of cleaning, a new gasket and back together.



Not surprisingly it's a lot smoother to drive now with power restored to previous levels. The death-rumble I had at 1500rpm is diminished to just an annoyance. Despite starting cleanly even with this damage the compression on #3 must have been down to petrol levels.

The cylinder liner damage is a concern. I had originally intended to pull the engine for a full rebuild with factory matched liner kits. Time wasn't amenable so this was a stop-gap.
But the sights I have just seen do not fill me with joy or confidence that this block is worth rebuilding.
I am now concerned that the bores which have been sleeved and bored by an automotive machinist will likely not match the factory specs even on the largest grade of liners.
I am faced with potentially thousands of dollars in machining to fix this problem and then throwing thousands more ($2k for 4x factory piston/ring/liner kits) with no guarantee of success.

So instead I'm looking into Isuzu factory long-blocks. Complete built replacements from rocker cover to sump.

But for now it's back and running very well considering. It starts even quicker than before and the pistons have shown that 750C EGT with the occasional excursion to 900C are no problem. On the test-drives so far the cooling system is holding it's drink and it's smoother and quieter to boot.

So I've been looking for intercoolers. Just looking, not buying.
I have no body lift so clearance to run pipes to the front without hacking the body is just non-existant. But even if the body weren't a problem, there's no clean run for piping of ~2.5" from the turbo to the engine and back.

So I did some measuring of the existing radiator while I had it out for a clean after the head-gasket. I decided I can relocate the AC condensor forward, fit a 50mm thick intercooler full width in front of the radiator and push the radiator back only 25mm.

So I started playing around in 3D. I found a few CX racing intercoolers where the shape looked like it might work and modelled them up. I also modelled up the radiator from my 1993 rangie. It's huge compared to the 85 original. Here is the pictorial:



The two sitting together in the middle is what I thought would be ideal. A 600x400x50mm intercooler core, the tanks on the side take it to about 800mm wide. I've got about 810mm between battery trays.
I'd then need a narrower intercooler to sandwich against that intercooler and miss the inlet/outlet pipes as they fly straight across the top from turbo to intercooler then back to inlet manifold.

I also did some calcs on heat exchanger sizing and found out that 600x200x80mm one in front can strip about 85% of the heat out at 2000rpm and 25psi boost, but can only do about 60% at 4000rpm and 33psi boost (just in case ).
I checked the numbers on my hypothetical intercooler of 600x400x50 core and it should be 70 odd percent at 4000rpm. Good enough.

But where do I find such a beast. Turns out, ebay have exactly that. Cosworth RS500 intercoolers.
Package up with the cosworth aftermarket radiators too.

Ford Sierra RS Cosworth 2WD 4WD RS500 Intercooler uprated Alloy Radiator Fans | eBay



Ignore the fans, I know the value of shrouding. But holy crap this is what I thought I'd never find and have to custom make.
The intercoolers start at ~$200 plus freight.

It was a long time ago, and the vehicle has long gone, so my memory is a bit vague.

I used an intercooler with side facing inlet and outlet. Then the hose elbow ran into the space above the front body mount, between the spaces for the radiator and the headlight.

I had to move a couple of things such as the power steering reservoir. IMHO that is the best arrangement with a rangie or disco.

Originally Posted by Bush65

It was a long time ago, and the vehicle has long gone, so my memory is a bit vague.

I used an intercooler with side facing inlet and outlet. Then the hose elbow ran into the space above the front body mount, between the spaces for the radiator and the headlight.

I had to move a couple of things such as the power steering reservoir. IMHO that is the best arrangement with a rangie or disco.

If I didn't have AC or remote mounted filters I'd have done that already.

The AC compressor is mounted below the alternator on the passengers side and that whole area is crowded out with the hoses, receiver/drier and lines from the condensor to the body and back again.
On the right hand side my remote filters are just above and behind the PS box with no easy pipe routing there either.

It could still be done with all that stuff, but it'd be really convoluted, take more work and make access to everything even more difficult. Which to be honest is why I still haven't done it.
Compounding that my radiator looks to only have a few more years in it. The RS500 parts are close to perfect.

I should add. I was very ready to start cutting to fit a conventional intercooler in front just before I found the 1993 rangerover which means an eventual body swap.

Setting up a complete cooling unit as a bolt together (AC-Intercooler-Radiator-Fans) will mean a lot less work when I swap bodies.

Today I did the old mountain range run again and even with the head-gasket sorted and the coolant not reaching worrying temps the oil gets thin enough to leave the oil light on at idle.
This trip is up to ~1800m altitude and the last 12km are average 1:10 interspersed with rocks and gates.
Meaning slow progress, no cooling wind, AC on and mostly 2nd-3rd gear high range. The altitude also means thinner air, higher EGT and less cooling both through and around the engine.

I'm really hoping a good intercooler and alloy radiator will help this.

For comparison. Drive an 80 series landcruiser up there and the auto over-heats.

I went back through my electric fans yesterday to see why they aren't sucking as hard as they should be.

I found a bad earth and melting fuse which made the difference between 10amps, 11 volts and 16 amps 13.5 volts. This doubled their power.
They are now sucking as hard as toyota corolla/corona parts usually do.