Thread: 4BD1 oil cooler.

Unless turbocharged, the Isuzu is not that much more powerful than the six, but has two significant advantages from the cooling perspective - diesels are inherently more thermally efficient than petrol engines, and there is always more air passing through than with a petrol engine producing the same power, giving more cooling via the induction.

With this particular diesel, the large thermal inertia compared to the six means short term overloads of the heating will not raise the temperature significantly.

Given these factors, I would not worry about inadequate cooling. With the radiator the same size as the V8, with my Isuzu I spend more time trying to keep it up to operating temperature rather than worrying about cooling. Even with a new thermostat I need to keep the radiator 80% shuttered in winter.

John

Hands up anyone who has overheated an Isuzu in normal use?

Anyone?

Diesel heat rejection can be half of a similarly powered petrol. Overheating is really only a problem for those with indirect injection toyota diesels.

Originally Posted by Lotz-A-Landies

Just getting all the info straight.

I still don't think the the Rover radiator will be sufficient to cool the 4BD1, as the Rover 6cyl get warm with them and can not see that the Isuzu will run cooler than the Rover donk.

The oil filter on the 4BD1 is externally mounted. Can I tap into the pipework and fit a thermo bypass valve?

This way the isuzu runs with it's standard oil cooling system for normal running, however if the engine starts getting hot the valve opens bypassing the oil through the external oil/air heat exchanger before returning to the engine. This will allow additional cooling when needed, using an original Rover 7 row cooler, without having to butcher the original bodywork to fit a larger radiator.

if the radiator is the same at the series petrol 6 pot it will be up to dealing with a stock rated 4bd1. unless your stupid with it and decide that just because it can haul your IIB with a full load on it up a 6 mile hill at 30% incline with a fully laden trailer on the tail at 50kph ona 40 degree day with no wind in top cog its damn well going to. flush it out keep the fins clean and you'll be fine.

I've personally seen one, exactly one over heated isuzu engine (theres even a post about it). I've heard of maybe 3 or four others.

Originally Posted by Dougal

[snip]
Overheating is really only a problem for those with indirect injection toyota diesels.

and the indirect injected TD42T in the Patrol

I've lost count of Perentie's I've passed with those huge yellow banners across the bullbar saying "Driver under Instruction" ( or something similar) most are towing trailers & I've always wondered how many overheat coz its a perfect blind.
Either that or the Isuzu is well & truly catered for with what radiator they have.

theres enough airflow around them as the barwork put the sign around 8-10 inches in front of the grill.

Ive seen one that had the radiator half caked with clay still not over heat (did run noticabley warmer though)

Just adding my 2.2c aswell Diana, a Rover 6 cyl petrol engine is VERY inefficient, unlike a Diesel like the 4BD1 etc. To overheat a diesel like this, one would need to wind the fuel screw out a LONG way and have WAY too much smoke emanating, have a partially blocked rad the size of a Datsun 120Y's cooling system, and be towing a 30 foot trawler up a steep hill.
I have to fit a thermostat to mine to get it to warm up and stay warm here in Tas, and even towing 1.2T at 100km/h in 42 degrees with a leaking water pump the gauge only reached half. ( I do have a EFI RR rad though, but it is behind 2 lightforce 240's, a bug screen, an intercooler, an A/C condenser and fans and it isn't all the clean, either )

I know you already know this, but Just make sure the rad is free of blockages and the thermostat is OK and all should be well

Happy Isuzu-ing

JC

Diana, You have more trouble keeping a 4BD1 at operating temperature than worrying about overheating one. You must have a good thermostat in one of these engines. They won't perform and achieve good economy unless they are warmed up properly.

Mine has gone up the Toowoomba in summer with 3/4 ton in the back and a laden No.5 on behind never below 60 kph in 2nd with only a minimal rise in temperature