Thread: Defender 110 county with 4BD1 diesel

The opening in the air cleaner you describe is the dust/water drain and should have a rubber fitting that lets dust/water out but nothing can get back in because of the "duckbill" feature of the rubber. If it is missing get a new one as this negates the effect of the snorkel. There is no way that air can bypass the filters by coming in this hole, it will suck air/dust/water but everything still has to go through the 2 filters.
With the breather, there has been quite a few threads on here about it. Do a search on 4BD1 breather and you should find them. It is normal to have a fair bit of breathing in these engines especially at idle. At those K's it is hardly run in! What it needs is some hard work. Get it out on the highway and give it to it.
Any pics?
What gearbox etc are you running behind it?

Thanks Brian. It's been off the road for 16 years a d I've been rebuikding for te last 5 on and off. Its done most f the major trips in standard form and never let me down.

LT85, LT230. I've made quite a few mods basically built my ideal off road tourer. Need to get a blue slip soon and then add a turbo and 3" exhaust system. I'll put some pics up once its got a blue slip plus a full list of mods.

Look forward to seeing the pics. PM me if you need any help with part numbers. That gearbox is not the best behind an Isuzu, especially a turbo version. Have a look around the forum here, there has been much said about boxes behind the Suzi. Minimum requirement for the LT85/LT230 should be a cross drilled gearbox output gear,careful use of 5th gear and using the correct oil. The original output gear on these had lubrication issues that results in wear on the gearbox output shaft indicated by banging/backlash on gear changes.

Mmmmm interesting - i had the LT85 rebuilt by all 4x4 in Kotaraa couple ofyears back in the build. There's a fair bit of clonking on gear change (always was) i always put it down to a bit of slack in the diffs. What's the "correct " oil. What's a cross drilled gearbox output gear.

Originally Posted by fid-def

Mmmmm interesting - i had the LT85 rebuilt by all 4x4 in Kotaraa couple ofyears back in the build. There's a fair bit of clonking on gear change (always was) i always put it down to a bit of slack in the diffs. What's the "correct " oil. What's a cross drilled gearbox output gear.

If it was rebuilt you would expect that the output shaft splines would be ok so maybe the slop is elsewhere in the driveline. Did they do the t/case at the same time? Centre diff gears,u/j's, cv's,diffs and drive flange to axle, plus A frame ball joint and suspension bushes are places to look for wear. Drive flanges are a common one. With the t/case oil, my advice would be to do a search on the site here as there is plenty of advice on different types. Synthetic 75W90 seems to be the go. Cross drilled gears are available to replace the standard gearbox output gear in the t/case which runs on the gearbox mainshaft. Originals suffered from insufficient oil getting to the splines under the gear and consequently wearing the splines. The crossed drilled gear has a couple of holes drilled in it to allow oil to reach the splines. If you have a fair bit of "clonking" I would be investigating where it is coming from. Hope this helps.

Thanks Brian a few things to think about there.

I do have one other question. With a cold engine i have oil pressure of 450 kpa (65 psi) at tickover and 480kpa (69 psi) at max revs. With a hot engine i have 250kpa (36psi) at tickover rising smoothly up to 480kpa at max revs. Is that normal??

Minimum oil pressure for the 4BD1T is 14 psi at idle, I assume the 4BD1 is similar. If it is yours looks fine.

Any idea why the difference in pressure at tickover between cold nd hot