D24T timing damage on 940TDI

GrahBark · Apr 10th, 2009, 13:03

I have had both the cam belt and fuel pump belt changed on this VW LT engine. It had been running perfectly up to then. The last time the belts were changed was 80,000 miles ago so I thought it was time to renew them.

Having got the car back the cold starting was poor and, over the following two weeks, grew steadily worse, ran unevenly at low speeds and it kicked out a load of white smoke from the exhaust. I was on my way to take it back to the garage when I heard a clattering noise from the engine. Then the engine stopped. Both belts were still tight.

Six days later they diagnosed the problem: the woodruff key built into the crankshaft gear (sprocket) had worn away, causing the engine timing to slip. They replaced this with a new one, started the engine and have now diagnosed top end damage.

They have had this repaired at a specialist engineer who cleaned up the head and supplied new hydraulic gear to go beneath the camshaft.

What I want to know, please, is: how can the woodruff key in the crankshaft gear wear away when it is held in place with a large bolt? I think I know the answer to this one but I would welcome a second opinion.

The garage claims that the woodruff key must have been wearing for some time and that this occurrence was due to happen soon, whether the belt was renewed or not.

Have you any experience of this happening before?

And on top of all this, the garage is now claiming there's a fault with the pump because it was kicking out white smoke and now, after adjusting it, the emissions are blue and white, suggesting there is oil getting in there.

Clan · Apr 10th, 2009, 13:55

Yes seen this quite a few times on 940 and 850 5 cylinder version which is the same , caused by not tighening the large pulley bolt properly .
The crank pulley location is not by a woodruff key it is by a pip which locates in a recess in the cam belt lower pulley , they dont wear , they can only wear if the pulley is loose and it rattles around . I would guess they havent renewed the crank pulley bolt or tighened it up correctly , it has to be EXTREMELY tight , Volvo say 350 nm thats with a NEW bolt , the torque wrench fits on their Volvo special spanner tool which alone is a foot long ... You will never get it tight enough without a very long torque wrench .
If the pulley has been loose and wobbling around it will have its flat mating face damaged so may well come loose again , a pulley is over £200 ... did they replace that or just the toothed cambelt lower pulley ? Also if its been loose for a while the end of the crankshaft will be damaged .. did they replace the 4 small bolts which hold the cam belt lower pulley to the crank pulley? they are use once only stretch bolts and cant be used twice .
Why didnt they notice a "worn woodruff key" whilst they had it apart and it was in a bad way ?

These engines really must be looked after by a specialist when doing cambelt work ..

GrahBark · Apr 10th, 2009, 17:25

Thanks, Clan.

It was the crankshaft timing belt pulley they said had a built-in woodruff key that had worn over time. I suspected they had not tightened the bolt properly. They replaced the pulley (£43). I assume it's the bigger pulley for the alternator/steering pump belts that is £200?

The problem now is that, with the emissions being as they are, I'm concerned that the garage has done the same as before and that the new belt pulley is also allowing the timing to slip again. Apparently, when the mechanic took it for a 6-mile test run yesterday it was okay. Today the engine was not as quiet and was kicking out the white smoke...

They will expect me to pay for this.

Clan · Apr 10th, 2009, 17:42

I think all you can do is get someone independant to dismantle the pulley again and see what actual damage there is , yes the large pulley is around £200 +...

The bolt has to be extremely tight , a lot of people dont realise the huge acceleration / deceleration forces on the pulley when a diesel is running at low rpm .. the engine doesnt run at a constant speed as you would imagine , it runs in a series of violent jerks at low rpm ...

Laney760 · Apr 10th, 2009, 19:15

Quote:

Originally Posted by Clan

These engines really must be looked after by a specialist when doing cambelt work ..

My cambelt is only tensioned by the waterpump, assume it was ok that I had a non-specialist change mine?

Clan · Apr 10th, 2009, 19:29

Its not really the tensioning , its hoping they know how important it is to tighten the crank pulley bolt properly ..

jor · Apr 13th, 2009, 17:11

Someone is breaking a 940 TD with an apparently functioning engine.
Might be worthwhile having a look on the auction site just in case various bits are required for your car, only problem being that the location is in East Grinstead.

jor

v8volvo · Apr 15th, 2009, 07:50

There is no fault with the pump -- it's impossible that there could be oil getting in, because on a D24 there is no situation in which oil and fuel come near each other. They just don't have the timing set properly is all. Wrong timing can cause bluish smoke as well as white.

It sounds like you need to find a new mechanic, one who knows what he is doing when it comes to VW/Volvo diesels.

MRDART · May 8th, 2009, 08:24

Yes one of most common problems with these engines is the lack of proper maintenance.
Here in sweden most of them was serviced at the volvo garage when they really should have been turned into a Diesel specialist.
Thus the d24 series engines have a bad reputation they do not deserve.
I am going on my 5th d24 engined car and have only had one engine failure so far....
A D24tic engine in good condition makes a sound that is like music....
Especially with a 3 inch straight exhaust

Apr 10th, 2009, 13:03	#1
GrahBark I've Been Banned Last Online: Mar 2nd, 2024 21:23 Join Date: Apr 2009 Location: Halifax	D24T timing damage on 940TDI I have had both the cam belt and fuel pump belt changed on this VW LT engine. It had been running perfectly up to then. The last time the belts were changed was 80,000 miles ago so I thought it was time to renew them. Having got the car back the cold starting was poor and, over the following two weeks, grew steadily worse, ran unevenly at low speeds and it kicked out a load of white smoke from the exhaust. I was on my way to take it back to the garage when I heard a clattering noise from the engine. Then the engine stopped. Both belts were still tight. Six days later they diagnosed the problem: the woodruff key built into the crankshaft gear (sprocket) had worn away, causing the engine timing to slip. They replaced this with a new one, started the engine and have now diagnosed top end damage. They have had this repaired at a specialist engineer who cleaned up the head and supplied new hydraulic gear to go beneath the camshaft. What I want to know, please, is: how can the woodruff key in the crankshaft gear wear away when it is held in place with a large bolt? I think I know the answer to this one but I would welcome a second opinion. The garage claims that the woodruff key must have been wearing for some time and that this occurrence was due to happen soon, whether the belt was renewed or not. Have you any experience of this happening before? And on top of all this, the garage is now claiming there's a fault with the pump because it was kicking out white smoke and now, after adjusting it, the emissions are blue and white, suggesting there is oil getting in there.

Apr 10th, 2009, 13:55	#2
Clan Experienced Member Last Online: Yesterday 23:15 Join Date: Jun 2007 Location: L/H side	Yes seen this quite a few times on 940 and 850 5 cylinder version which is the same , caused by not tighening the large pulley bolt properly . The crank pulley location is not by a woodruff key it is by a pip which locates in a recess in the cam belt lower pulley , they dont wear , they can only wear if the pulley is loose and it rattles around . I would guess they havent renewed the crank pulley bolt or tighened it up correctly , it has to be EXTREMELY tight , Volvo say 350 nm thats with a NEW bolt , the torque wrench fits on their Volvo special spanner tool which alone is a foot long ... You will never get it tight enough without a very long torque wrench . If the pulley has been loose and wobbling around it will have its flat mating face damaged so may well come loose again , a pulley is over £200 ... did they replace that or just the toothed cambelt lower pulley ? Also if its been loose for a while the end of the crankshaft will be damaged .. did they replace the 4 small bolts which hold the cam belt lower pulley to the crank pulley? they are use once only stretch bolts and cant be used twice . Why didnt they notice a "worn woodruff key" whilst they had it apart and it was in a bad way ? These engines really must be looked after by a specialist when doing cambelt work .. __________________ My comments are only based on my opinions and vast experience .

Apr 10th, 2009, 17:25	#3
GrahBark I've Been Banned Last Online: Mar 2nd, 2024 21:23 Join Date: Apr 2009 Location: Halifax	Thanks Thanks, Clan. It was the crankshaft timing belt pulley they said had a built-in woodruff key that had worn over time. I suspected they had not tightened the bolt properly. They replaced the pulley (£43). I assume it's the bigger pulley for the alternator/steering pump belts that is £200? The problem now is that, with the emissions being as they are, I'm concerned that the garage has done the same as before and that the new belt pulley is also allowing the timing to slip again. Apparently, when the mechanic took it for a 6-mile test run yesterday it was okay. Today the engine was not as quiet and was kicking out the white smoke... They will expect me to pay for this.

Apr 10th, 2009, 17:42	#4
Clan Experienced Member Last Online: Yesterday 23:15 Join Date: Jun 2007 Location: L/H side	I think all you can do is get someone independant to dismantle the pulley again and see what actual damage there is , yes the large pulley is around £200 +... The bolt has to be extremely tight , a lot of people dont realise the huge acceleration / deceleration forces on the pulley when a diesel is running at low rpm .. the engine doesnt run at a constant speed as you would imagine , it runs in a series of violent jerks at low rpm ... __________________ My comments are only based on my opinions and vast experience .

Apr 10th, 2009, 19:29	#6
Clan Experienced Member Last Online: Yesterday 23:15 Join Date: Jun 2007 Location: L/H side	Its not really the tensioning , its hoping they know how important it is to tighten the crank pulley bolt properly .. __________________ My comments are only based on my opinions and vast experience .

Apr 13th, 2009, 17:11	#7
jor VOC 20573 Last Online: Jul 10th, 2023 22:14 Join Date: Mar 2007 Location: wembley	Someone is breaking a 940 TD with an apparently functioning engine. Might be worthwhile having a look on the auction site just in case various bits are required for your car, only problem being that the location is in East Grinstead. jor

Apr 15th, 2009, 07:50	#8
v8volvo New Member Last Online: May 2nd, 2013 08:38 Join Date: Apr 2009 Location: Seattle, WA	There is no fault with the pump -- it's impossible that there could be oil getting in, because on a D24 there is no situation in which oil and fuel come near each other. They just don't have the timing set properly is all. Wrong timing can cause bluish smoke as well as white. It sounds like you need to find a new mechanic, one who knows what he is doing when it comes to VW/Volvo diesels.

May 8th, 2009, 08:24	#9
MRDART Junior Member Last Online: Jan 19th, 2010 08:40 Join Date: May 2009 Location: Tomelilla	Yes one of most common problems with these engines is the lack of proper maintenance. Here in sweden most of them was serviced at the volvo garage when they really should have been turned into a Diesel specialist. Thus the d24 series engines have a bad reputation they do not deserve. I am going on my 5th d24 engined car and have only had one engine failure so far.... A D24tic engine in good condition makes a sound that is like music.... Especially with a 3 inch straight exhaust

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