Smokey 4JB1-T after long runs.

[bedford4x4]

G'day everyone,

I've had a long break from the forum due to a really intensive course I was doing. I finally finished the course and now ready to do some much-needed maintenance on the old truck, including both electric window winders, GRRRR!!!!

One thing which I have noticed is that while driving day-to-day around town, the truck doesn't blow any oil smoke. If I've been driving out on the highway for a while, the next time I start the truck it blows a big cloud of blue smoke. The motor starts first pop every time, so it shouldn't be rings.

A guy at Turbo-care in Christchurch says this is normal for 2.8 and 3.1 Isuzu diesels and reckons a catch-can sorts them out.

Is he right?

[mulover]

He sure is, these motors breath heavier than most, and when your just running around town its not putting out much oil through the tappet cover breather, but when you go on a decent trip, it will be putting quite a bit out, which coats the inside of the inlet manifold. When the vechile is sitting it runs into the top of the pistons and causes the big cloud of smoke when you sart it next time.

It does no harm, and if you can put up with the smoke, then dont worry about it, or a catch can will make a big difference. It won't totally stop it but it will reduce it a great deal.

[bedford4x4]

Hey thanks for that - I find it quite annoying, so I'll look at a catch can. Apart from that the motor runs really well.

2 owners before me someone put a Bighorn intercooler on, a 2 1/4" exhaust, freeflow muffler, rock sliders, front and rear raised bumpers, body lift, fuel tank lift, suspension lift front and rear and ball-joint flip on the front.

Cool wagon but I believe the tiny turbo can't keep up with the rest of the set-up at highway speeds. The guy at Turbo-care put a bigger turbo on his 3.1 and is now getting 140bhp (dynoed). I may do the same.

[mulover]

Your lucky, With a good set of tires thats about all you have to do to make these a great medium to hard club truck.

They aren't known for their top end speed, but there is enough room for a bigger turbo in there. Also try advanceing the timing a bit and increasing the fuel flow a bit if it hasn't been done yet.

[geeves]

That turbo will boost 14psi right up to just under 4000 and is still holding 12 at the rev limiter. If the turbo is good I wouldnt touch it. If you buy a second hand 3.1 turbo you are also buying a possible heat shield problem that can only be fixed with another turbo

[bedford4x4]

That turbo will boost 14psi right up to just under 4000 and is still holding 12 at the rev limiter. If the turbo is good I wouldnt touch it. If you buy a second hand 3.1 turbo you are also buying a possible heat shield problem that can only be fixed with another turbo

The guy at Turbo-care has a 3.1 Mu, and put a larger turbo body on his - that's why his is dynoed at 140bhp. The response is instant and the more you put your foot down in his wagon, the more it accelerates. It is amazing, really. Mine seems to have a slight lag before taking off, but that may be the fact that mine has an automatic and so doesn't get revved (and turbo spun up) momentarily before the clutch is let in. Turbo-care opened the fuel delivery up, but left the pump timing as standard.

My turbo is in excellent condition, boosting to 13psi on Turbo-care's gauge in around-town tests. The turbo-care guy says that the standard turbo is pretty small and may not be able to keep up with the other modifications (Bighorn intercooler, 2 1/4" exhaust, freeflow muffler) at high speeds. I just don't get the top speed sluggishness. Perhaps it's because the overdrive is so tall - I mean 2000rpm at 90km/h is nice to cruise along at but useless for overtaking. I have to manually chop it down out of overdrive.

Hence my interest in a larger turbo or a way of getting more air to the motor. Anyone had any experience of "Finer Filters" or other filters which improve airflow?

[geeves]

That is low revs for 90kph. The 4jb1t is still well under peak torque at those revs as it is a fairly high reving engine. (for a diesel) The 2.8 Mu should have 4.56 diffs and 31 inch tyres as standard especially so with the auto. It could be worth checking the diff ratios. Most other Mus Ive heard of are doing 3000rpm at 100kph My bighorn with the 31 inch road tyres and 4.3 diffs is doing 2400
Ive had a finner filter in my bighorn for about 5 years and it works well. A lot of people have also used cotton gause type filters like the K&N also with good results. On its own it didnt make much difference to performance but it did solve a problem of moisture coming down the snorkel destroying paper filters every 6 months. A far bigger improvement came from both the 2.5 inch exhaust and the snorkel. The Mu wont get as much out of the snorkel as the bighorn does as it already has a better intake setup. The big exhaust,intercooler and snorkel all help the turbo spin up better so will help the turbo not make it work harder to keep up.

[bedford4x4]

That is low revs for 90kph. The 4jb1t is still well under peak torque at those revs as it is a fairly high reving engine. (for a diesel) The 2.8 Mu should have 4.56 diffs and 31 inch tyres as standard especially so with the auto. It could be worth checking the diff ratios. Most other Mus Ive heard of are doing 3000rpm at 100kph My bighorn with the 31 inch road tyres and 4.3 diffs is doing 2400
Ive had a finner filter in my bighorn for about 5 years and it works well. A lot of people have also used cotton gause type filters like the K&N also with good results. On its own it didnt make much difference to performance but it did solve a problem of moisture coming down the snorkel destroying paper filters every 6 months. A far bigger improvement came from both the 2.5 inch exhaust and the snorkel. The Mu wont get as much out of the snorkel as the bighorn does as it already has a better intake setup. The big exhaust,intercooler and snorkel all help the turbo spin up better so will help the turbo not make it work harder to keep up.

Mine has 31" tyres, but I've no idea about the diff ratios. If I leave it out of overdrive it does about 3000rpm at 100km/h. The biggest difference seems to be when the torque converter locks up. It locks the torque converter up at 90km/h and the revs drop from about 2700rpm down to 2000rpm. I'd always thought it was crazy having such tall gearing on the vehicle. Makes for nice cruising, but sluggish acceleration in top gear unless I chop it out of overdrive. What would be better would be a way of unlocking the torque converter at will, so I could unlock it for overtaking.

I wonder if someone has changed the diff ratios?

thanks for the info on the filter set up. Actually, I ran the truck without a filter for a few kilometres just to see what difference it made - absolutely none that I could perceive.

[geeves]

I dont actualy belive that the high flow filters are any better than a near new good quality paper filter. The benifit comes from a longer service life and being cleanable.
You could put a switch in the wire that activates the lockup but it could muck up the computer.
Out of overdsrive it sounds about right

[mudgrip4]

If you have a snorkel and bigbore then airflow will be good. I would take it to a diesel shop andincrease the fuel flow. Ask him to advance the pump timing and increase the fuel, as mulover suggests above. This will add 15-20hp more if it hasn't already been done - and only takes 30 mins. Worked a treat on my bighorns.

RE your turbo, the 2.8 turbos are fine for your motor in even advanced tune though there are variations with 2.8s - VI58, VI74 and VI87. The VI58 is smaller, while the VI74 is evidently bigger, best. Turbocare could check this for you.

The catch-can addition is easy to do - you can pick them up off trademe etc for $40-70. Easy enough to fit, and good to add a drain tube from bottom of can down into dipstick tube. Makes a big difference.

[wbski007]

Don't laugh fellas but what the hell is a catch can and what does it do and I thought snorkels were just to keep water from entering your intake going through streams and such, do they serve another purpose, I don't know about , Wayne

[geeves]

Its a very simple device. A lot of isuzu diesels create a lot of crankcase fumes even though the engine is in good condition. This blows oil into the breather pipe which then runs into the intake and is burnt. The catch can is simpley a chamber that slows the fumes down so the oil drops to the bottom and can be returned to the crankcase.
They are also used on a lot of high performance engines.
Not all isuzu engines need them but if they burn a lot of oil this one mod will fix most

[wbski007]

thanks Geeves, I guess mine doesn't need a catch can, I change my oil every 3 thousand miles and it doesn't use any, I use Shell rotilla 15-40 diesel, been useing it for years,seems to work OK, and every 3rd oil change I add a bottle of Dura lube.

[geeves]

Mines the same but its only done 200000km

[mulover]

putting a catch can on mine made a big difference to the amount of smoke on start up, it only takes one drop of oil to make a big cloud of smoke!!

[kingman]

I also get that Smoke recently on mornings and on mornings the Holden starts up rather slowly then on start pufff smoke...but during the day it starts in a flash one swing.....could this be a sign of a problem to come??

Thus far the battery has been tested and is fine..What do yu guys think?

[wbski007]

could be you have a glow plug or two gone bad? I'd test them,
mine gets a puff in the mornings too but its black,not a lot tho,
cheers

[mulover]

Glow plugs would be where i start, if i'm right, you'll probably be getting a blacker coloured smoke, as it will be un-burnt diesel.

[mudslinger]

valve stem seals

[geeves]

Ive been testing a few 3.1 engined vehicles lately and not one of them has had even the tinyest puff of smoke on start up even from cold.
Could be glow plugs (faulty or not waiting for the light to go out) Could be oil in the manifild due to blow by (catch can will help) Could be low compression (rebuild) Could be injector or pump issue.
What mileage?