Cam belt tension

JonK · Post by **JonK** » Tue May 15, 2007 17:12

Hi all,

I seem to have a lot of belt noise on my Excel and I am worried that the cam belt may be tensioned incorrectly (too tight).

I have looked through the service notes and they specify a specific belt tension tool which I am guessing will be hard to get.

So can anyone tell me if it is possible to check the cam belt tension after it has been fitted/tensioned and also can anyone recommend a tool for the job.

Jon

tonycharente · Post by **tonycharente** » Tue May 15, 2007 18:34

Hello,
If you do a search on "cambelt change" you'll find lots of answers already on the forum.
It's not all that "technical" to do - it just takes ages...
Cheers
Tony

Skeggy · Post by **Skeggy** » Tue May 15, 2007 20:40

Jon,

have a look at here

Number 12 gives you the info you need to do it without special tools.

Just a word of caution if your are in anyway concerned about the cam belt then don't use the car until your have checked it out - cam belt failure will destroy the engine.

Steve

chrisw2811 · Post by **chrisw2811** » Tue May 15, 2007 21:19

Burroughs gauges aren't easy to get hold of, but a rule of thumb that seems to work well is that a correctly tensioned belt should deflect about 80 degrees around its axis in the middle of the run between the auxiliary (distributor) pulley and the inlet pulley. If it's tight so that you cannot turn it very far then it will whine and if it is significantly looser (i.e. rotates past 90 degrees) it will flutter, especially on the overrun. You could take off the belt cover and check by twisting. However, your post suggests that the tension was previously OK. It seems unusual that the tension should increase, as a worn belt should get slacker. Therefore I would suggest taking off the cover and looking very carefully at (a) the belt, checking for loose teeth or wear marks on the belt, (b) the pulleys to make sure they haven't developed any sharp edges (which apparently can happen) and (c) anything that gets close to the belt, such as the cover, power steering hose near the exhaust cam pulley and assorted wires, to make sure nothing is rubbing on the belt.

amarshall · Post by **amarshall** » Tue May 15, 2007 21:23

Jon - I suffered from extreme belt noise last year - it got louder until the car sounded like a steam train. The crank pulley teeth had sharpened and were destroying the NEW belt rapidly.

JonK · Post by **JonK** » Wed May 16, 2007 08:25

Thanks for the excellent advice as always.

I am dying to check this out now, so no doubt this will make my very long day of training even longer.

jonno · Post by **jonno** » Wed May 16, 2007 09:18

JonK,

I changed mine last week. The link to the technical article given by Skeggy was extremely useful. I used the tippex and counting teeth method. I adjusted the tension so the twist was just less than 90 degrees, and the engine runs okay. However, I will be getting my freindly Lotus man to double check it when its time for its MOT.

Redexcel · Post by **Redexcel** » Wed May 16, 2007 13:36

JonK wrote:Hi all,

I seem to have a lot of belt noise on my Excel and I am worried that the cam belt may be tensioned incorrectly (too tight).

I have looked through the service notes and they specify a specific belt tension tool which I am guessing will be hard to get.

So can anyone tell me if it is possible to check the cam belt tension after it has been fitted/tensioned and also can anyone recommend a tool for the job.

Jon

You can buy something called a Krikkit gauge from any motor factor that is an agent for Gates belts, although they may have to order it, once you have convinced them it is available. Unfortunately, I do not know the exact model name, but there are others on this forum who do and actually own such a beast. (Please speak up !!)
The Krikket gauge is is a viable alternative to the official Lotus tensioning tool, the Burroughs gauge, but is much cheaper to buy.
It is also calibrated differently, but again, there are those on here who can tell you the correct settings.

This is probably the most accurate and cost-effective way of tensioning the cambelt. Best of luck

Stefan · Post by **Stefan** » Wed May 16, 2007 18:59

Hi, thats my tool

You need a Krikit KR1 model number 91107 I got mine in USA for 8$, but it shuld not be hard to find it in UK, it's a Gates product, and should be in your Lotus Excel glove compartment.
Here it is: http://www.gates.com/europe/brochure.cf ... on_id=2976
I found out how to use it from the Jensen-Healey forum in the states, and it's been a very handy tool, being able to rutine check the cambelt (takes 1 minute) at a regular basis, just checking at TDC every month.

In basic:
Cold engine 15-25 degrees C
Test between auxillary pulley and intake cam pulley
Test at TDC, 120 and 240 degrees and take an average, this is important since the belt tension is not constant cranking the engine around.
Average reading should be 52 Krikit, a new belt could be set at 55 Krikit.
At 50 Krikit retension, dont drive below 46 Krikit.

After the first time i did this i went to a Lotus service place to check and be on the safe side and the tension was ok.
But of course i do not take any resposibility in what i write..

JonK · Post by **JonK** » Wed May 16, 2007 20:05

Good news!!

I have checked the belt tension and it was very tight!

I have released the tension to something more reasonable and what a difference. The engine sounds so much better.

I noticed a Gates agent in Basingstoke so I will try to get hold of a Krikit tool and then I can check it regularly.

Thanks Stefan for the detailled information (and RedExcel).

I have a Swedish Colleague going to USA in a couple of weeks so if I can not get hold of one I will ask him to check over there and bring one back.

Skeggy · Post by **Skeggy** » Wed May 16, 2007 20:12

JonK wrote:...
I have a Swedish Colleague going to USA in a couple of weeks so if I can not get hold of one I will ask him to check over there and bring one back.

Jon,

Very glad you got it sorted.

How large is your colleague suitcase

I'll put my name down for one at the dollar price

Steve

JonK · Post by **JonK** » Wed May 16, 2007 20:34

Stefan,

Can I just check with you that the link is to the right version of the tool.

It does state that it is not suitable for timing belts. Although I do realise that this is probably just a covering statement I thought I'd better check before I go a hunting

Jon

Stefan · Post by **Stefan** » Wed May 16, 2007 22:07

Yes, its the correct one, very easy to fins in US, most larger car parts stores got it.
But just checked price it's $17(USD)
Heres another interesting web page on the subject:
http://www.espritfactfile.com/timingbelt2.html

Stefan

chrisw2811 · Post by **chrisw2811** » Mon May 21, 2007 11:00

Brammer stock Krikit gauges in the UK - 01902 395000

chrisw2811 · Post by **chrisw2811** » Wed May 23, 2007 17:47

£14.93 plus post/packing...

The Lotus Grand Tourers

Cam belt tension

Cam belt tension

Re: Cam belt tension