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Hi all,
I’m hoping someone can help with getting to the root cause of the rattle on my 1990 pre March 2.3 20v 7a CQ. I’ve exhausted all the historic threads on here and other forums, and I’m at a point where I’ve pretty much run out of ideas. The actual issue I’m having is a nasty rattle at around 1100rpm with a simultaneous cam belt slap between the cam sprocket and water pump, as well as between the idler and cam sprocket. I’ve located the noise at the distributor by listening through a pry bar. The same kind of noise is present at very very low volume above and below 1100rpm and not as aggressive. It’s only audible through the pry bar at the distributor as well as the valve cover. You can hear the very loud noise at 1100rpm at the valve cover through the pry bar but it’s not as loud as at the distributor.
I’ll detail the journey below in chronological order. Some things I’ll mention won’t necessarily be relevant, but I’ll include them just to paint a full picture. I’ve paid very close attention to vacuum leaks, replaced a lot of hoses, crankcase breather etc etc and the car drives beautifully. It pulls where it should and doesn’t misfire.
When I bought the car it was well over due a cambelt change, so that was the first job on the list. The noise wasn’t present before doing the cam belt job. Within that job I changed the following:
Cam belt - Gates 5182XS
Water pump - SKF VKPC 81606 (only one available at the time. Would like to change it to a Hepu pump)
Crank pulley - Chef’s
Cam shaft oil seal - Elring (maybe Corteco, can’t remember)
After I changed these, the noise was bad and was present maybe from 1100rpm to 2000rpm (ish). This is going from memory 5 months ago, but I do recall it being worse than it is currently. I’ll note here that I can’t remember the point where it did get slightly better and sit pretty much at 1100rpm only, +/- 50rpm.
Phase 1
I thought it would be the obvious distributor gear and end float issue. I removed the distributor and the plastic gear was intact but split, and there was excessive end float. I bought a metal gear from Ultra Automotive
https://ultra-automotive.co.uk/new-d...2019-uk-stock/
They supplied me with various shims to dial in the end float. I did the replacement, shimmed within spec and the noise persisted but the pitch changed. This makes sense going from a plastic to metal gear. I re-shimmed the distributor around 4 times and there was no change every time. The rotor arm that was fitted was loose, so I thought that might be the issue so I sourced the correct arm which push on firmly and no change. I also changed the cap for a Bosch one. I sent the distributor to Ultra Automotive for them to check the condition and refurb the internals if necessary, but they reported it was in working order and the end float was correct. I bought a second distributor which was untouched, plastic gear and end float within spec but there was no change whatsoever. At this point, I’ve pretty much ruled out the distributor as the issue.
Phase 2
The next theory was the cam chain being slack. I ordered a Febi chain and once installed it was obvious the previous chain was somewhat slack, but not excessive. While I was there, I changed the tappets for INA 68g 420002210 (1911043038).
This all made the top end lovely and quiet, but the noise and cam belt slap was still present.
Phase 3
I’d run the car for abit at this point, maybe travelled 50 miles or so driving it on the weekends and started to wonder if cam belt tension was the issue. I stripped the front end down and after removing the cam belt cover I noticed the belt had walked towards the engine. So much so that it’s put a groove in my valve cover. I noticed that the lip on the crank pulley had completely come off. I’m not sure what happened first, the belt walk pushed the lip off, or the lip came off allowing it to walk. Regardless, Chef sent me another one with some spot welds on the lip this time. After replacing that, I tensioned the belt correctly, too tight and slightly too loose (safely) for testing. I noticed that the noise did not change, although the belt slap did, which I’d assume it would do. It did not fix the slapping altogether though, just changed it.
Phase 4
Clutching at straws at this point, I thought maybe the idler was the culprit. I had intended to change it on the original belt change but it wouldn’t shift so I left it. I removed the belt and spun the idler by hand and it did feel stiff but not rough. I thought maybe it was creating drag and causing the belt to slap. Something I found interesting is that it was the incorrect idler that was fitted. It was a 68mm idler rather than the correct 74mm idler. I used the INA 22009601. Installing this made the natural tension on the idler to cam sprocket side feel much better. After this was all done, the noise may have changed ever so slightly, although it may be me just hoping it had changed, so let’s just say there’s no difference at this point.
This was the last thing I tried and I’m pretty much stuck at this point. The only other area I can think it might be is cam shaft end float related. Although not a thorough test, I tried measuring the axial end float at the cam sprocket with a DTI. I say this isn’t a thorough test as the belt was still fitted and tensioned. I’m also not clued up enough to know if the end float can be measured this way, or if I have to removed the valve cover again and measure inside with the belt removed. The result of the measurement was dead zero. Again, if I can take the measurement externally like this, I understand the belt tension may not allow me to do so.
I can’t think of anything else to add and I’m pretty sure I’ve covered everything I’ve done so far. Maybe the last things to note is that there was no visible wear on the cam shaft gear that meshes with the distributor gear. It does instinctively feel like this is the exact point that the noise is coming from, but like I said, I’m really not sure at this point. I really can’t tell if the issue is elsewhere and travelling back to the distributor. The cam oil seal also isn’t pushed all the way back as far as it’ll go. It sounds like I’m saying it’s incorrectly seated, what I mean is I installed it flush with the valve cover with space behind it. So, I’m fairly confident the positioning of that isn’t causing an issue, if that’s even something that could cause cam shaft end float issues.
I’d be extremely grateful for any input from anyone. I’ve owned the car for 5 months and I’ve been chasing this issue pretty much from day one since doing the cam belt job. It’s even more discouraging to know that it hadn’t had a belt changed in 10 years, it was very very loose and the incorrect idler was fitted, yet it didn’t have this nasty rattle noise!
Thanks,
Reece
I’m hoping someone can help with getting to the root cause of the rattle on my 1990 pre March 2.3 20v 7a CQ. I’ve exhausted all the historic threads on here and other forums, and I’m at a point where I’ve pretty much run out of ideas. The actual issue I’m having is a nasty rattle at around 1100rpm with a simultaneous cam belt slap between the cam sprocket and water pump, as well as between the idler and cam sprocket. I’ve located the noise at the distributor by listening through a pry bar. The same kind of noise is present at very very low volume above and below 1100rpm and not as aggressive. It’s only audible through the pry bar at the distributor as well as the valve cover. You can hear the very loud noise at 1100rpm at the valve cover through the pry bar but it’s not as loud as at the distributor.
I’ll detail the journey below in chronological order. Some things I’ll mention won’t necessarily be relevant, but I’ll include them just to paint a full picture. I’ve paid very close attention to vacuum leaks, replaced a lot of hoses, crankcase breather etc etc and the car drives beautifully. It pulls where it should and doesn’t misfire.
When I bought the car it was well over due a cambelt change, so that was the first job on the list. The noise wasn’t present before doing the cam belt job. Within that job I changed the following:
Cam belt - Gates 5182XS
Water pump - SKF VKPC 81606 (only one available at the time. Would like to change it to a Hepu pump)
Crank pulley - Chef’s
Cam shaft oil seal - Elring (maybe Corteco, can’t remember)
After I changed these, the noise was bad and was present maybe from 1100rpm to 2000rpm (ish). This is going from memory 5 months ago, but I do recall it being worse than it is currently. I’ll note here that I can’t remember the point where it did get slightly better and sit pretty much at 1100rpm only, +/- 50rpm.
Phase 1
I thought it would be the obvious distributor gear and end float issue. I removed the distributor and the plastic gear was intact but split, and there was excessive end float. I bought a metal gear from Ultra Automotive
https://ultra-automotive.co.uk/new-d...2019-uk-stock/
They supplied me with various shims to dial in the end float. I did the replacement, shimmed within spec and the noise persisted but the pitch changed. This makes sense going from a plastic to metal gear. I re-shimmed the distributor around 4 times and there was no change every time. The rotor arm that was fitted was loose, so I thought that might be the issue so I sourced the correct arm which push on firmly and no change. I also changed the cap for a Bosch one. I sent the distributor to Ultra Automotive for them to check the condition and refurb the internals if necessary, but they reported it was in working order and the end float was correct. I bought a second distributor which was untouched, plastic gear and end float within spec but there was no change whatsoever. At this point, I’ve pretty much ruled out the distributor as the issue.
Phase 2
The next theory was the cam chain being slack. I ordered a Febi chain and once installed it was obvious the previous chain was somewhat slack, but not excessive. While I was there, I changed the tappets for INA 68g 420002210 (1911043038).
This all made the top end lovely and quiet, but the noise and cam belt slap was still present.
Phase 3
I’d run the car for abit at this point, maybe travelled 50 miles or so driving it on the weekends and started to wonder if cam belt tension was the issue. I stripped the front end down and after removing the cam belt cover I noticed the belt had walked towards the engine. So much so that it’s put a groove in my valve cover. I noticed that the lip on the crank pulley had completely come off. I’m not sure what happened first, the belt walk pushed the lip off, or the lip came off allowing it to walk. Regardless, Chef sent me another one with some spot welds on the lip this time. After replacing that, I tensioned the belt correctly, too tight and slightly too loose (safely) for testing. I noticed that the noise did not change, although the belt slap did, which I’d assume it would do. It did not fix the slapping altogether though, just changed it.
Phase 4
Clutching at straws at this point, I thought maybe the idler was the culprit. I had intended to change it on the original belt change but it wouldn’t shift so I left it. I removed the belt and spun the idler by hand and it did feel stiff but not rough. I thought maybe it was creating drag and causing the belt to slap. Something I found interesting is that it was the incorrect idler that was fitted. It was a 68mm idler rather than the correct 74mm idler. I used the INA 22009601. Installing this made the natural tension on the idler to cam sprocket side feel much better. After this was all done, the noise may have changed ever so slightly, although it may be me just hoping it had changed, so let’s just say there’s no difference at this point.
This was the last thing I tried and I’m pretty much stuck at this point. The only other area I can think it might be is cam shaft end float related. Although not a thorough test, I tried measuring the axial end float at the cam sprocket with a DTI. I say this isn’t a thorough test as the belt was still fitted and tensioned. I’m also not clued up enough to know if the end float can be measured this way, or if I have to removed the valve cover again and measure inside with the belt removed. The result of the measurement was dead zero. Again, if I can take the measurement externally like this, I understand the belt tension may not allow me to do so.
I can’t think of anything else to add and I’m pretty sure I’ve covered everything I’ve done so far. Maybe the last things to note is that there was no visible wear on the cam shaft gear that meshes with the distributor gear. It does instinctively feel like this is the exact point that the noise is coming from, but like I said, I’m really not sure at this point. I really can’t tell if the issue is elsewhere and travelling back to the distributor. The cam oil seal also isn’t pushed all the way back as far as it’ll go. It sounds like I’m saying it’s incorrectly seated, what I mean is I installed it flush with the valve cover with space behind it. So, I’m fairly confident the positioning of that isn’t causing an issue, if that’s even something that could cause cam shaft end float issues.
I’d be extremely grateful for any input from anyone. I’ve owned the car for 5 months and I’ve been chasing this issue pretty much from day one since doing the cam belt job. It’s even more discouraging to know that it hadn’t had a belt changed in 10 years, it was very very loose and the incorrect idler was fitted, yet it didn’t have this nasty rattle noise!
Thanks,
Reece
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