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3.1 TD - 4JG2 - how to replace water pump...


 
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AndyGault
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Joined: 22 Jun 2010
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PostPosted: Thu Nov 15, 2012 22:29    Post subject: 3.1 TD - 4JG2 - how to replace water pump... Reply with quote

...without removing timing belt cover - no aircon, manual gearbox

I've got loads of information from this site (thanks guys!) so I thought I'd give something back.

Recently my water pump started weeping so I ordered a new one from Milners.

Here's how I changed it without removing the crank pulley and timing belt covers. My crank has a 24mm nut that's b*****d tight and has to come off before the crank pulley will come off. So I decided to try it without removing it...

The 4JG2 water pump is driven by the v-belt that runs crank-alternator-fan. It is NOT driven by the timing belt but you can't get to all its bolts without manipulating the timing belt cover.

I'll also include removing the radiator cos a) it's easier to do the job, b) you're draining the coolant anyway, and c) it saves you putting a spanner through your radiator like I did, and having to buy a new one.


Ingredients

1 x new water pump
7-14mm ring spanners, open spanners and sockets. (12mm ring spanner essential for keeping sanity)
2 litres antifreeze and some water
4 x new M6 bolts
A hacksaw (or Dremel if you have one)
Loctite
A bucket
A crowbar or similar
A mallet

Process

1. Remove the fan (4 x 10mm nuts). Don't drop them. Manipulate the fan out from behind the shroud.

2. Drain the coolant. There's a drain plug at the bottom of the radiator, or just pull the bottom hose off. Use the bucket to catch it in.

3. Remove radiator top hose and the small hose that attaches by the filler cap. Remove the filler cap.

4. Undo clips and remove fan shroud.

5. Remove bottom hose.

6. Remove 2 x bolts that hold the radiator on to the front panel.

7. Lift out radiator. Don't lose the rubber mountings that are on the bottom radiator feet.

8. Put radiator somewhere safe. Don't hit it, knock it over or otherwise upset it or you'll put a hole in it.

9. Now to remove the v-belts. slacken off 2 x bolts on power steering pump bracket (the ones facing the front of the car) and loosen the adjuster until you can get the belt off. Remove the idler pulley (belt goes crank-idler-power steering pump) as it'll make life easier later. 21mm socket if i recall correctly.

10. Slacken alternator tensioner fixing bolt (faces the front of the car) and loosen the tensioner bolt. Get the crowbar (or similar) and lever the alternator back toward the engine. If it doesn't move you may need to slacken the mounting bolts.

11. Remove the alternator belt. These often *only just* fit so they can be a pain to get off.

12. pull fan pulley off water pump. If it won't move, encourage it with the mallet. There's nothing holding it on to the water pump now, so it should come off.

13. Now you should have the water pump hub/flange exposed - sort of a disc with threads sticking out of it. Undo as many of the timing belt cover bolts as you can find. Most of these are 10mm but one or two on mine were 12mm. some are longer than others so try to remember where they came from. It'll be obvious if you put em back in the wrong place cos they either won't bite or they'll stick out.

14. The water pump is held on by 5 or 6 loooong bolts and 2 nuts. Undo and remove all the ones you can get to.

15. Gently prise the timing cover away from the engine so you can get a ring spanner to the remaining 3 bolts and 1 nut. This is fiddly but not too hard. DO NOT drop any bolts or nuts inside the timing cover or you'll be taking the crank pulley off after all. You'll find that all but one of the bolts aren't too bad to get out... the bottom left one (as you look at the pump) is the hardest. You'll need to undo it all the way then twist your way out. It is possible - i've done it twice.

16. Water pump removed, time for a cuppa.

17. With mine, the old water pump had M6 threads attached to the hub. The new one didn't. So I got the 4 x M6 bolts and cut the heads off so that the thread is about the same length as the ones in the old pump hub. A hacksaw will do this, a Dremel is easier! Put these to one side for a bit.

18. Clean up the edges of the engine block where the old pump mated with it.

19. Put the pump gasket (you'll get one with the new pump) into the groove, bend the timing cover a bit and slot it over the two studs. Make sure the gasket is still intact as it's easily moved. The front left bolt is again the hardest one to get in... once you've done that one put the rest of the bolts in, nuts on and tighten. Put all the bolts back into the timing cover.

20. Note that you're going to put 4 threads into the pump BUT there are 8 threaded holes. These are spaced differently - if you look really carefully you'll see that 4 of them are slightly closer to the edge of the pump hub than the other 4. Make sure you put the threads you made (step 17 above) into the right holes or your pulley won't fit! When you know you have the right ones (just screw them in to the pump then offer the fan up to them - it should go on easily - then remove the fan cos we're not ready for it yet) whip the threads out, stick a bit of Loctite on them and screw them back in so the thread is flush with the back of the hub. Leave them alone whilst you get on with other stuff.

21. Put the radiator back in. Make sure the rubber feet are still on it, and attach the bottom hose (NOT the top one yet). Put the radiator bracket back on to secure it.

22. Put the fan shroud back on - slots in the bottom and clips on the top.

23. Attach the top hose and the small hose that attaches by the filler cap.

24. Mix coolant as you need to (i did 25-35% ish with water) and tip it into the radiator until it's full. Fill the expansion tank to the "MAX" mark too if you need to.

25. Refit fan pulley over water pump threads and put belt on crank-alternator-water pump. Don't tighten it yet.

25. Refit idler pulley and refit power steering belt. Adjust power steering belt and secure pump bracket bolts (reverse of step 9)

26. Refit fan - it will slot over the threads and secure using the 10mm nuts.

27. Tension alternator belt firstly by levering it away from the engine then by using adjuster on alternator. If your adjuster bolt has vanished, an M8x80 bolt should do the trick. Don't adjust it too tight or you run the risk of breaking the alternator or the new water pump, in my case it failed on the M11 near Harlow. Manual says 10mm deflection in the belt when applying 10kg of load to the longest part; so to be safe I adjusted it so it was a little too slack then nipped it up the following morning when it squealed like a pig on heat. Easy enough to do.

28. Assuming your radiator is now full (per step 24), leave the radiator cap off and start the car. Run it at about 2,000 rpm. Check for immediate leaks from around the water pump. If you did it right it should stay dry. The water level in the radiator will drop - top it up to the bottom of the neck. When the thermostat opens and it starts warming up the radiator it might start foaming - stick the radiator cap on and let it run for a good 15 mins.

29. Let the car cool down FULLY and top up again if necessary. It'll probably take a bit more coolant but then that should be it.


Looks pretty daunting but once you've figured out what's where it's pretty straight forward. I did points 17 onwards in just over an hour in the dark with a headtorch on.

If anyone has any mods to add to this, such as extra steps for autos and aircon-equipped trucks, please feel free to add detail Smile
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PostPosted: Thu Nov 15, 2012 22:29    Post subject: Google Ads keep this community free to join!


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d12
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PostPosted: Fri Nov 16, 2012 22:07    Post subject: Reply with quote

well any leaks or did it work out ? hope it did
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AndyGault
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PostPosted: Fri Nov 16, 2012 22:31    Post subject: Reply with quote

d12 wrote:
well any leaks or did it work out ? hope it did

Yeah all good ta  Very Happy
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sambo90
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Joined: 30 Sep 2015
Posts: 4
Location: Somerset

PostPosted: Thu Oct 01, 2015 19:30    Post subject: Reply with quote

Hello!
First post as a user. Just bought my first trooper a 3.1 LWB citation with the 4JG2 engine.
The engines come with a water leak, i new this when i bought it, apparently the chaps local garage said its the waterpump / gasket, judging by what i can see id say they are right!
Ive got the water pump and im going to give it a go on sunday.
My question is, is taking the crank pulley off such an issue? ive read the above guide, but it seems to involve quite a lot of fiddling. Does taking the crank pulley off involve alot? does it effect the timing? on my old hilux i could get the timing cover et al off without effecting the timing?
i think that makes sense...
Basically, why not just take the crank pulley off?
Cheers
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Rhanagar
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Location: Preston, Lancs.

PostPosted: Thu Oct 01, 2015 23:36    Post subject: Reply with quote

Crank pulley comes off by removing the 4 off 12mm bolts arrayed around the main bolt in the middle. People get confused because they remove the four bolts but it has seized on so it can take quite a lot of swearing to remove. Once off take a wire brush to the mating surfaces, and brush/scrape the crud off. Then slap a load of copperslip between the pulley and crank when refitting.
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1990 Isuzu Bighorn LWB Mk.I 2.8TD Manual Lotus Edition
1994 Isuzu Bighorn LWB Mk.II 3.1TD Auto Lotus Edition

Deceased
1994 Isuzu Bighorn LWB Mk.II 3.1TD Auto LS

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Rhanagar
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Posts: 4859
Location: Preston, Lancs.

PostPosted: Thu Oct 01, 2015 23:38    Post subject: Reply with quote

This timing belt change guide goes into more depth:

http://www.itocuk.co.uk/forums/viewtopic.php?t=27458
_________________
1990 Isuzu Bighorn LWB Mk.I 2.8TD Manual Lotus Edition
1994 Isuzu Bighorn LWB Mk.II 3.1TD Auto Lotus Edition

Deceased
1994 Isuzu Bighorn LWB Mk.II 3.1TD Auto LS

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