V8 Cambelts - check em!
Discussion
All V8 owners,
As most know, the V8 requires cambelt servicing every 12,000 miles or 12 months. One recent owner had cambelt failure on 1997 V8 with less than 11,000 miles and is looking at a serious repair bill.
I've been on top of mine since new and in the past 9 months, I've managed to hit 33K miles since the last service at 18K miles (about 3,000 miles past due... oops). I decided that while I was yanking stuff apart, I would pull the covers and check the belt tension. They were so loose they were literally flapping on the run between the drive pully and the tensioner!
I doubt they got this loose in the past 3,000 miles as they are tensioned at 95-120 Hz. So I think they need to checked more frequently than the 12K interval currently being spec'd. In any case, I decided to take care of this now and get the engine back together so I can continue on with other things.
I made a set of timing pins and a tool to adjust the tensioners and after getting the belts tight again (just snug really) the cam timing is almost dead-on (whew).
I'll be putting a small setup together later to measure the belt tension (finally to get play with some audio toys) and we'll see how that works. So once the car is functional again, I'll schedule for the 36K miles cambelt service.
As a side note, the 23mm hex shanks on the camshafts are not true, infact all 4 of mine are different sizes, 3 are larger than 23mm, 1 a bit smaller and all blocked by a head bolt/tower casting from access with a wrench. Hence you really need the full toolset if you intend to loosen the cam pulleys.
So to all you V8 owners out there, if you can't remember when you're last cambelt service was, get them in NOW (regardless of mileage) and be safe.
Regards, KM
2000 V8 - in cocoon state
As most know, the V8 requires cambelt servicing every 12,000 miles or 12 months. One recent owner had cambelt failure on 1997 V8 with less than 11,000 miles and is looking at a serious repair bill.
I've been on top of mine since new and in the past 9 months, I've managed to hit 33K miles since the last service at 18K miles (about 3,000 miles past due... oops). I decided that while I was yanking stuff apart, I would pull the covers and check the belt tension. They were so loose they were literally flapping on the run between the drive pully and the tensioner!
I doubt they got this loose in the past 3,000 miles as they are tensioned at 95-120 Hz. So I think they need to checked more frequently than the 12K interval currently being spec'd. In any case, I decided to take care of this now and get the engine back together so I can continue on with other things.
I made a set of timing pins and a tool to adjust the tensioners and after getting the belts tight again (just snug really) the cam timing is almost dead-on (whew).
I'll be putting a small setup together later to measure the belt tension (finally to get play with some audio toys) and we'll see how that works. So once the car is functional again, I'll schedule for the 36K miles cambelt service.
As a side note, the 23mm hex shanks on the camshafts are not true, infact all 4 of mine are different sizes, 3 are larger than 23mm, 1 a bit smaller and all blocked by a head bolt/tower casting from access with a wrench. Hence you really need the full toolset if you intend to loosen the cam pulleys.
So to all you V8 owners out there, if you can't remember when you're last cambelt service was, get them in NOW (regardless of mileage) and be safe.
Regards, KM
2000 V8 - in cocoon state
I just adjusted my cam belt (4 cyl), and it was as loose as you describe. On the Krickit guage, I guestimate it to have been around 10 lbs (53 lbs recommended). It flopped too. A minor PITA to do, to be sure. Especially when you drop a socket down the front of the motor and it takes you a couple hours with a mirror and a drop light to find it.
I have an idea on a 4 cyl cam belt tensioner adjusting tool:
Take a 19mm socket, bore it out so that just the last 1/4" has "grip", weld a handle on it bent in such a manner that you can get it up on the 19mm adjuster nut, take a 17mm socket turned down to fit inside the 19mm if necessary, weld a handle on it bent such that with it inside the 19mm socket, you can turn and tighten the nyloc nut.
With a setup like this, I think I could take the alternator belt only off, drop the belly pan and while laying under the car, get to the tensioner and be able to manipulate the tensioner/lock nut without having to take the plenum and alternator off. Anyone ever try this?
Dr.Hess
I have an idea on a 4 cyl cam belt tensioner adjusting tool:
Take a 19mm socket, bore it out so that just the last 1/4" has "grip", weld a handle on it bent in such a manner that you can get it up on the 19mm adjuster nut, take a 17mm socket turned down to fit inside the 19mm if necessary, weld a handle on it bent such that with it inside the 19mm socket, you can turn and tighten the nyloc nut.
With a setup like this, I think I could take the alternator belt only off, drop the belly pan and while laying under the car, get to the tensioner and be able to manipulate the tensioner/lock nut without having to take the plenum and alternator off. Anyone ever try this?
Dr.Hess
V8TT said:
So is there a way to temporarily tighten them inbetween services ?? If so can you please explain how ??
Thanks !
AL
You shouldn't have to, but it's very important to keep the frequency of cambelt services consistent. In short, never more than 12 months or 12K miles. Unless you want to experience difficulty, stress and a lot of detailed work in inadequate spaces, you should just let the dealer do it. To tighten them can be a lengthy process....
You need to remove the serpentine auxillary belt and tensioner, water pump pulley and power steering pump pulley (makes it easier) and then remove the three covers to gain access to the belts and adjusters (you may need to move the front plumbing out of the way as well). You will need a few unusual tools in addition to the usual stuff. A short torque wrench for the tight area and a special tool to fit the holes in the belt tensioner. I made one from some steel stock along with a set of 4 timing pins to check the cam timing once setting the crankshaft into proper position from underneath.
You really need to get the manual to gain a better idea of the procedure as it can be very involved depending on how much stretch of the belts has occurred and how badly the cam timing is off. In my case, the timing was extremely close to dead-on, just stretch in the belts. Be aware that Lotus recommends the use of a clavis gauge to tension the belts within a specific frequency range (like a guitar string) and that tool alone is in excess of $1K.
In short, it's not something I'd recommend to every V8 owner... to do it properly requires some special tools, good skills and a lot of patience. After all, one mistake and you can sratch one engine.
Regards, KM
2000 V8
PS - I suggest you get yours up to Al at PBMC and get it done. Arrange with Dave Simkin first and it should be free.
Well, I would hardly say Lotus got it wrong. Consider the fact that the 918 engine is exceptionally compact in all dimensions for a 32-valve quad-cam V8 with twin turbocharging and weighs in at a very light 485 pounds complete with all ancilliaries, wiring loom, flywheel/clutch and packs a real wallop even detuned.
Seems a small price to pay and if maintained properly, cam timing is generally spot on and has vitually no timing jitter. Adding chain drives and/or autotensioners would also add weight and would eventually develop timing errors from stretch, albeit at a much slower rate than the belts. The 918 also has hydraulic tappets which are both very compact and require zero maintenance.
So in short, the only maintenance on the V8 is fluids, filters, cam belts and spark plugs. Not a bad deal for a high-tech exotic hand made engine.
Regards, KM
2000 V8
Seems a small price to pay and if maintained properly, cam timing is generally spot on and has vitually no timing jitter. Adding chain drives and/or autotensioners would also add weight and would eventually develop timing errors from stretch, albeit at a much slower rate than the belts. The 918 also has hydraulic tappets which are both very compact and require zero maintenance.
So in short, the only maintenance on the V8 is fluids, filters, cam belts and spark plugs. Not a bad deal for a high-tech exotic hand made engine.
Regards, KM
2000 V8
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