Thread: 4bd1 swap

Originally Posted by bushhack

i have a 4bd1t in my landrover at the moment cooked the rings on it, found a cheap replacement but it is a non turbo. which means the there is no oil drain for the turbo. can i drain the turbo back in to the vacuum oil return? if not can i drain it to one of the side plates where the breather is?
also is the breather below the exhaust manifold required on a turbo motor ? will the breather on the rocker cover be good enough??
thanks

The vac pump oil return will not work (too much oil flowing through already).

Here is what I did, which has worked well for years now:
http://www.aulro.com/afvb/isuzu-land...tml#post812089

I believe others have used the side plates.

You can blank off the lower breather using one of the side plates from your T engine, but you MUST also fit the entire rocker cover assembly from the T engine, as it is ~19 mm diam vs ~8 mm for the na rocker cover.

great thanks for that i did come across a thread all about oil return lines
http://www.aulro.com/afvb/isuzu-land...drain-etc.html

I'm currently using the rear side plate as a drain for a centifugal filter. I have a rocker cover from a later 4B motor but will probably set up an extra breather from the front side plate.

How bad is the 4BD1T? I'd rather rebuild it in-situ (I've done pistons/rings/liners in frame before in a weekend) than swap to a non turbo and try to make everything fit.

i downloaded a manual and i think all it needs is liner, rings and pistons
ill pull the head off and have a look at it dougal do you have a thread or photos on the rebuild??
do you have a liner puller ??
oh and can i reuse the head bolts? i know many cars have yeild bolts one time use but being a truck motor different

I don't have any pictures, but if you have done any engine work before it's quite straightforward. I have made a liner puller, I'll look for the drawing later. They are quite easy to make on a big enough lathe.

The head bolts can be re-used, mine have been many times. The manuals have different torquing methods for new vs used head-bolts.

Check out the recent thread on piston/liner clearances, but if you have downloaded the manual you have this information anyway.

okay so i pulled the engine out, took the head and sump off and popped the pistons out
liners 2 and 3 have severe scouring/ scratches where the rings have welded them selves to the piston
crank looks fine so ordered a rebuild kit planning to swap out bottom end bearings while i am at it and replace clutch trust bearing

oh and 2 of my valve spring retainers had split causing the spring to push past the retainer a bit! talked to the head recon guy he said it the first time ever seen any thing like it. possibly from "valve float". which is when the rockers are pushing the valves down as they are still coming up. so if any of you guys are giving the old 4bd1 a bit of a hard time keep it in mind.

Originally Posted by bushhack

okay so i pulled the engine out, took the head and sump off and popped the pistons out
liners 2 and 3 have severe scouring/ scratches where the rings have welded them selves to the piston
crank looks fine so ordered a rebuild kit planning to swap out bottom end bearings while i am at it and replace clutch trust bearing

oh and 2 of my valve spring retainers had split causing the spring to push past the retainer a bit! talked to the head recon guy he said it the first time ever seen any thing like it. possibly from "valve float". which is when the rockers are pushing the valves down as they are still coming up. so if any of you guys are giving the old 4bd1 a bit of a hard time keep it in mind.

Stock valve springs are quite strong because the Isuzu trucks have exhaust braking - so valve float in an application without exhaust braking and with stockish boost pressures should not normally occur.

Stronger valve springs (after market chevy V8 can be made to fit) are required if running high (30 - 40+ psi) boost pressure and 4000+ rpm. The 110 lb chevy V8 springs are good for around 50 psi boost and 5000 rpm in a 4BD1T.