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  #1  
Old 06-13-2021, 08:22 AM
Bob Bob is offline
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Vehicle: 740 wagon, 164 saloon
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Unhappy cambelt query

hi guys
i hope someone can help me, i have recently bought a volvo 740 estate with a d24tic engine. (it had a swap from the later variant so the mk2). i got it running and decided to do the cambelt as it had been off the road for 12 years. anyway after 3 months trying to source one and too many missing parcels later i bought it in parts. i got gates belts, febi idler, qh tensioner, FAI water pump. anyway here's the problem. im getting it done ive got it timed up and locked the crank to 600nm (as i don't have the crank extension too) but i noticed that the idler pulley doesn't sit quite square in the hole, in other words the hole isn't center of the idler causing it to pull sideways when tight and to add to this the threads seem to be stripped but there are a few at the back so i can get it tight enough. i have managed to square it up as much as i can by removing a burr from where the old idler was mounted, it looks as if the old one has heated up and possibly span causing the surface to wear unevenly. now the other concern the belt rides off the water pump slightly by a couple of mm which is an improvent from when i first mounted the idler. this happens slowly if i rotate the engine 10 revs or so. everything seems relatively true now as per pictures but im not sure if this overhang of the belt is acceptable. perhaps the water pump isnt quite correct or the idler mounting is causing issues. in addition what do you suggest i seal the idler bolt with. ptfe, loctite thread lock or a loctite thread sealant. i just dont want to do anything silly so i thought id get in touch with the specialists who may know better[IMG]https://ibb.co/khTbC36
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Last edited by Bob; 06-13-2021 at 12:53 PM.
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  #2  
Old 06-13-2021, 11:12 AM
jpliddy jpliddy is offline
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Default 940 tic auto 1995

hi i have the later version of your cam belt set up with tensioner too . post 1993
the cam belt to me should be just a milimeter back from outside face ,as mine is ,why it wants to ride so close to the back face is beyond me ,the idler i have never seen mine is just in centre of idler ,but the tensioner has a off set centre im sure, some one here will know whats the cause of your problem im sure .
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Old 06-13-2021, 12:50 PM
Bob Bob is offline
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hi thanks for your feedback. slightly less concerned now cheers. when you say 1 mm back from the outside face does that mean it overhangs on the engine side of the waterpump by 1mm or is it 1mm until it reaches the back edge of the waterpump, or the belt is 1 mm back from the front sprocket/ wp

Last edited by Bob; 06-13-2021 at 12:58 PM.
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  #4  
Old 06-14-2021, 08:33 AM
v8volvo v8volvo is offline
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Good eye on catching the idler not sitting square, that is important.

The idler needs to be seated into its recess by tapping it in with a mallet. Pulling it in with only the bolt is not enough to get it all the way in, and can lead to it going in crooked as well. I have experienced this too.

Have you tried seating it that way?
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Old 06-14-2021, 08:46 AM
Bob Bob is offline
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Quote:
Originally Posted by v8volvo View Post
Good eye on catching the idler not sitting square, that is important.

The idler needs to be seated into its recess by tapping it in with a mallet. Pulling it in with only the bolt is not enough to get it all the way in, and can lead to it going in crooked as well. I have experienced this too.

Have you tried seating it that way?
hi v8volvo
thankyou for your reply.
yes i have tried tapping it in gently however the hole seems off center when the idler is tapped in square as you may be able to tell from the photos. i thought perhaps the idler hole itself is not completely central and thus you have to put the idler in a certain way to match the block. but if not i cant understand why the hole is not center. the only way the hole is centre is when the idler is placed on the piss if you like and obviously if you tightened it at that it would pull the idler even further out of alignment. I'm not going to lock it up until i know its all correct as we dont want another broken d24. thanks again for your reply.
bob
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Old 06-16-2021, 10:44 AM
jpliddy jpliddy is offline
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Default 940 tic auto 1995

hi bob
my belt sits just back for the front face of the cam sprocket only about a millimetre don't want it over lapping that sprocket if you get what i mean .
regards jim
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  #7  
Old 06-23-2021, 08:57 AM
v8volvo v8volvo is offline
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Quote:
Originally Posted by Bob View Post
hi v8volvo
thankyou for your reply.
yes i have tried tapping it in gently however the hole seems off center when the idler is tapped in square as you may be able to tell from the photos. i thought perhaps the idler hole itself is not completely central and thus you have to put the idler in a certain way to match the block. but if not i cant understand why the hole is not center. the only way the hole is centre is when the idler is placed on the piss if you like and obviously if you tightened it at that it would pull the idler even further out of alignment. I'm not going to lock it up until i know its all correct as we dont want another broken d24. thanks again for your reply.
bob
When I have more time this weekend, I will take a look at one of my engines to compare with your photos. I think you are right to be very careful about this. If the alignment is indeed off then serious problems could result.
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Old 06-23-2021, 01:22 PM
Bob Bob is offline
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hi, i have improved it by centralizing the idler to the pump with a Dremel and the idler now seems square as i have measured it with a straight edge, how accurate this is i am not sure so i couldn't guarantee it isn't still causing the issue. I'm pretty sure the oil pump is still at fault. id like to fit a new one however apparently the tic pumps are slightly different. I can find lt35 ones on ebay but they have a flat face whereas like mine and yours there is a recessed bore for the idler. i may end up taking the pump to a machine shop and getting them to square the bore and dti the outer edge of the idler to ensure its true to the pump. I may have to ally weld it first as you can only remove material. the only other potential cause i can think of is the tensioner as if it is not tight the belt runs true and sits nicely on the cam sprocket. i have a quinten hazel tensioner however i fitted the old litens one and it does the same so im doubtfull its a quality issue. judging by the wear marks/ polished areas on the cam sprocket it seems to have been running slightly off for some time. im planning on firing it up at the weekend and keeping an eye on the belt with someone in the car ready to switch off. if it throws a wobbly ill be on the lookout for a new pump and oem tensioner. FINGERS CROSSED
regards
bob
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  #9  
Old 06-27-2021, 10:49 AM
jpliddy jpliddy is offline
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Default 940 tic auto 1995

hi just looking at photo number 7 your car must be different set up as my idler roller is in the centre of roller
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  #10  
Old 08-15-2021, 11:59 AM
Bob Bob is offline
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Default UPDATE. no further forward...

regretfully after further work conducted to the engine i still have not managed to prevent the cambelt walk. the work completed or parts tried and installed would include the following
1. 1x Quinten hazel tensioner 1x febi tensioner ( febi one had significantly less preload on the belt tension).
2. febi idler pulley
3. FAI water pump
4. new crank and cam drive sprockets
5. gates belts
6. oil pump idler mounting machined and sleeved with a steel insert.
The reason i replaced the drive gears was because i noticed they were visibly worn at the back from where the belt had been previously riding and i figured that the combination of both top and bottom worn gears could encourage the belt to ride back however the new gears did not solve my issue.
the oil pump was machined by a friend of mine as the hole was not central when the idler was inserted for some reason. so he bored it out square and machined a steel insert for the idler to ride in to keep the original measurements the same. this was a good time to change the sump gasket. (what a game) not something i enjoyed in the driveway in the rain.however that didn't solve my issue.
i am beginning to come to the end of my tether with this fault as no matter what i try and ultimately spend does not fix my issue despite my best intentions.
so, i was thinking i noticed that the older waterpumps have two flanges either side of the gear. this would help the belt to stay on course in the event of the belt walking i thought and i was wondering if anyone knows if i could fit an older flanged gear onto my pump to limit the belts movements. i would buy one second hand if possible from a forum member.
also when i removed the rear cam cap to time the cam i noticed there was significant float probably a few mm but once the rear cap is installed it seems to locate the cam in a fixed position.

that's the situation for anyone following, open to ideas from anyone who has had a similar issue.

ta
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