4jb1 cambelt repair question

[isuzuser]

Hi, I have a SWB 1990 Bighorn with the 2.8intercooled engine.
I have changed the cambelt and pulleys but have a few questions before I finish it..
I have fitted the cambelt, covers etc and started it up briefly. It seemed to go ok (phew!). I only have to fit the fan, waterpump and belts etc
I have fitted the alternator belt again but have trouble tensioning it .
My questions are:

1.How the hell do you tighten up the alternator bolt that locks the tension onto the belt? I got the alternator undone but I'm having difficulty getting the alternator locked in place once I apply the tension to it. I have taken the battery tray out to get access to it but dont seem to have the tool that can fit in there and tighten it again. Is there some knack to it or special tool?

2. For tensioning the cam belt I did not strictly follow the 9kg weight reccomendation that the instructions say to put on that tensioning lever attached near the camshaft tensioner pulley. I didnt have any measuring device so took the word of a mechanic who said it was "about right". I'm now paranoid that it might be too tight or too loose, it was pretty firm and roughly about how firm the old cambelt seemed when I took it off but as for 9kg.. I wouldnt know.. How critical is this tensioning?

3.I think I got the belt back on in the correct position because it seemed to start and run ok for the very short time I ran it. Would it be obvious if I had the belt just one notch out or would the difference be quite subtle, like just a bit more smoke and a slightly more noise or something?

SOrry for the basic nature of these questions. I havn't done this job before so im a bit paranoid that I have got it right so I dont stuff the engine and would appreciate your advice.

[pig75]

10 liters of water is 10kg just tie a bucket to the tenison arm
have you read the FAQ? viewtopic.php?f=27&t=172

[geeves]

Mechanics word is likely to be ok They do thousands of these on other cars. Mine was done by touch by a mechanic friend. Too loose it might slip and too tight will wear the idler but there is a high margin of error.
The alternator is a pain easiest way is to grow another arm but this isnt for everyone. Ive always done mine by jamming a large screwdriver between the alternator and block and useing this to tension the belt while tightening the bolt. You can remove the aircon pump to get more room but this is a fiddle as well. Expect skinned knuckles.
The cambelt to do by the book means fitting a locking bolt through the hole in each pulley which means you cant go wrong but you can also do it by counting the teeth but be careful this way. If the injector is out it will run but could overhear and knock. If the cambelt is out it may run but you risk valve damage

[Demonic]

Do you have a list of the componants you replaced? Plan on doing my one very soon too.

[pig75]

The only thing you need is a timing belt. Unless there are fan belts or seals that are worn

[mulover]

Also do the tensioner pully/bearing thing too, they cost very little to replace.

[isuzuser]

Thanks Pig and Geeves.. I have now got the alternator belt on and tensioned. I thought it would be plain sailing from here on in but the friggin bolt (that came out so easily!) that is the tensioning bolt for what I think is the power steering pump (on the right hand side of the motor if you are facing it) is proving a bit of a pain in the arse to get back in. Its frustrating because its nearly there but not quite lined up enough for the bolt to thread into the nut. I'll get it eventually with a bit of jiggling but shit.. It was a lot easier to take out than put back . It seems like it has come out of alignment a bit. Also the bracket part of it that has the nut attached to it looks slightly bent. This might be the problem but more than likely I think that is just how it is and I just need to apply pressure to it in the right way.

Geeves, I was trying to go as by the book as I could, and I was happy there was a sure fire way to bolt the cam and injector pulleys in place. I locked one but I swear the other didnt have a screw hole.. I was bamboozled by this because i was sure that it wouldnt have been left off but I looked at it over and over and the pattern of holes on the injector pulley was not the same as the pictures in the manual or ones I have seen on this site. I dont know whats happening there. It said to use M8 bolts to secure the pulleys. one pulley had the facility for this but the other only had the casting pattern holes plus one 3-4 mm hole which didnt go all the way through the pulley. I managed to jerry up a solution to stop it moving but it was because of this that I became a bit paranoid about getting the belt on the wrong tooth just in case I got it slightly wrong.

Demonic, I replaced the cambelt, the idler and the tensioner pulley, the alternator belt and the two fan belts. I purchased and did intend to replace the camshaft seal as recommended by the parts shop guy but in the end I forgot to put it in so took it back and got a refund. Buggered if Im going to go through all this again to put that little thing in, no matter now important it is. It's probably worth noting that as I understand from the parts guy, the 4jb1 engine can have either a square toothed or round toothed cam belt. I purchased both so i knew I had the right one when I opened the engine. Mine turned out to be the round toothed one so I returned the other. If I were you I would do the two pulleys and not just the cam belt while you have the engine in bits because the parts are relatively cheap and equally important as the cambelt if they fail. Some say to do the water pump too but I took a punt that it is fine. I have nice clean coolant, no funny noises from it and the car doesnt appear to run hot at all.. I took a chance or else where do you stop? Maybe I should check the head gasket and crankshaft bearings and piston rings while im at it?.
The cam belt was $40 the idler was $60 and the tensioner bearing was $70 the Camshaft seal that I didnt use was $11 the fan belts were $20 each I think and I cant remember the price of the alternator belt. Hope this helps.

The most annoying this of this whole effort was that the cam belt and pulleys looked to be in really great shape when I took them out. Apart from a bit of dust and grime they were pretty much indistinguishable from the new parts in terms of wear etc.

I probably didnt have to do it at all... Oh well.. at least I know it has been done now eh..

[geeves]

One intersesting question. Your profile shows a bighorn with a 4jg2 engine but this post refers to a 4jb1. The round tooth belt is the same on both engines but the square is only for the 4jb1

[isuzuser]

Geeves, I have two bighorns now,
when I first signed up I only had a mark 2 bighorn 3.1 . I had problems with it shortly after buying it with a bolt from the torque converter getting stuck in the ringear and making the whole engine appear siezed. This incident made me think I had brought a lemon, as the exhaust gasket and cambelt needed doing too, so I purchased a cheap Mk1 bighorn 2.8 manual because it seemed cheap in the meantime, which seems to run very nicely but it didnt have service history, hence the (apparantly unnecessary) cam belt change.

Maybe I should update my profile to include the mk1 bh aswell. I will be selling one of them soon probably.

[Demonic]

To do the water pump does it need the cambelt removed or can it be done at a later date?

[pig75]

Just the plastic timing cover needs to be removed to change a water pump

[geeves]

Unlike some brands waterpumps on isuzus are not a over common repair. They do fail but not at any set time or mileage. I also have a Toyota and a company corrolla Both lost pumps at 180000km. Ones a 90 the other a 97

[Demonic]

Seems my speedo was wound back an even 10,000kms, cos the T-belt light came on yesteday at 190,000 km,
anyway. guess ill be doing a cambelt this weekends. Just want to confirm that all ill need is 1x cambelt and 1x tensioner yeah?

Can people from NZ please tell me you partnumbers for a 4jb1 and were you got them from?

The bottom pulley needs the 4 small bolts removed yeah? or so i need to undo the cranknut and remove with a harmonic puller?
Then its just turn engine over(by hand) untill the holes like up and lock off ALL the pulleys, old belt off, new belt on, am i missing anything?

[geeves]

Pretty much. Dont know how expensive the tensioner is most are cheap but mines still original at 202000. True on everything else but your belt could be either one. You wont know till you open the cover. Its most likely the square tooth but no guarantee.
Still a good idea to mark the belt and teeth before you start just in case

[Demonic]

And what about the bottom pulley? just the 4 bolts or does the whole thing need to come off?

[pig75]

just the 4 bolts

[Demonic]

Wooo... Hooo .. Cambelt saturday! , its not like I could be our 4x4ing or anything exciting you know!

I got a full cambelt kit from BNT, includes belt, tensioner, idler, and 3 seals. cost was a little over $300, my question is (before i start on this) for the seal to be done on the bottom shaft does that big bugger of a bolt need to come out? or once again is it just a matter of removing the 4 bolts?

[geeves]

Not sure but I think so. You will see as soon as you start. Remember when putting this bolt back 152 foot pound and it mattters

[Demonic]

Yes you do need to remove the bolt to do the seals, However after consulting my mechanics they (2) told me that unless the area around the seal is wet not to worry about the seals.

I have taken a few photos of of the cambelt area with the covers off and pullys locked with a bolt, will put them in here for future reference to anyone who needs them.

One thing that got me was everyone said set the tensioner to 9kg, however the manual says 10-12kg., i went 10 to be in the middle.

[Demonic]

Quick pic of pulleys locked just before removal of old belt.