[Rock2001]

I'm about ready to actually replace the timing belts, and so before I started I measured the current belt tension frequency to ensure I know what I'm doing. Initially I had some issues getting reliable frequency values from TuneIt, but then I realized that it was something else that I haven't heard anyone mention. When I move the crank to 80 and 120 degrees and measure, it starts at usually between 130 and 160hz. Now if I keep tapping the belt it comes down to the target 120hz, and I can hear it change so it's not the mic or software. Is that normal? It seems like if I tap the belt a number of times it finds some equilibrium and then the measurement is reliable, and where it should be.

Also just so I'm absolutely sure, the RH bank is the passenger side, right? I initially got confused as I'm looking from the front of the motor.

Thanks
Rock

 

[esprit888]

I think you made a typo, if you are looking at the FRONT of the motor then the RH bank is on your left or passenger side. If you are standing at the REAR of the car with the hatch up and engine cover off then the RH bank is on the passenger side. I have no knowledge of your mechanical competency but the V8 timing belts are way more complex and require specialized tools when compared to the 4 cylinder versions. Not one to learn on the hard way.

I'm about ready to actually replace the timing belts, and so before I started I measured the current belt tension frequency to ensure I know what I'm doing. Initially I had some issues getting reliable frequency values from TuneIt, but then I realized that it was something else that I haven't heard anyone mention. When I move the crank to 80 and 120 degrees and measure, it starts at usually between 130 and 160hz. Now if I keep tapping the belt it comes down to the target 120hz, and I can hear it change so it's not the mic or software. Is that normal? It seems like if I tap the belt a number of times it finds some equilibrium and then the measurement is reliable, and where it should be.

Also just so I'm absolutely sure, the RH bank is the passenger side, right? I initially got confused as I'm looking from the front of the motor.

Thanks
Rock

 

[Eric Rogers]

I'm about ready to actually replace the timing belts, and so before I started I measured the current belt tension frequency to ensure I know what I'm doing. Initially I had some issues getting reliable frequency values from TuneIt, but then I realized that it was something else that I haven't heard anyone mention. When I move the crank to 80 and 120 degrees and measure, it starts at usually between 130 and 160hz. Now if I keep tapping the belt it comes down to the target 120hz, and I can hear it change so it's not the mic or software. Is that normal? It seems like if I tap the belt a number of times it finds some equilibrium and then the measurement is reliable, and where it should be.

Also just so I'm absolutely sure, the RH bank is the passenger side, right? I initially got confused as I'm looking from the front of the motor.

Thanks
Rock

How are you moving the crank between those positions? Are you just moving it back and forth? If so, that's your problem. You are supposed to spin the engine twice and stop at the correct position and then measure. I hope you aren't turning the engine backwards, that's a no no, and you will have to report to this thread so Beerman can berate you:
http://www.lotustalk.com/forums/f164/separating-talk-fiction-bs-231681/

 

[carbuff]

Usually, accuracy with the frequency method depends on a position in the engine's cycle where normal forces don't "influence" the reading.

For example, spark plugs are supposed to be removed. (Don't want compression to try and move the belts.) Likewise, cam positioning can also attempt to move the belts if it is improper. Something like this appears to be what you are seeing.

I only know the 4 cylinders, but for that engine the plugs must be removed and the crank set at 30 BTC yada yada. If these conditions are not met, the readings would be inaccurate or change as the timing belt is "strummed".

 

[jtrealty]

Positioning the crank exactly in the right position is critical to getting accurate, repeatable measurements. You cannot eyeball it close. You should follow the procedure exactly. All positions are as you are sitting in the driver's seat so the passenger side of the car is the right side and the right hand bank of cylinders is also on the right side of the car. Confusion can creep in if you are under the car upside down looking rearward. The right side becomes the left. To do the belts requires some special tools, mostly necessary to position the crank. If you are not going to do it correctly my advice is not to do it. An error will be a lot more costly than having it done by a shop.
David Teitelbaum

 

[Rock2001]

OK, so RH is passenger side, that's what I thought and just wanted to confirm. I am turning the crank only CW, no back and forth. I didn't see the manual say to remove the plugs, but that makes sense and I'll try that. I am waiting for the crank positioning tool before I start, but I just wanted to do a quick test. So I eye-balled where the crank positioning tool would lock the crank and put the timing disk on relative to that (just for now, I'll do it officially once I get the tool), but that might have put me a couple of degrees off. Since Lotus decided to change the tensioning position by 10 or 15 degrees (from 90 to 80 degrees, and 135 to 120 degrees) I wouldn't think a couple degrees off would really show anything. But certainly, I'll reset everything once I get all the parts.

But so the short answer is nobody has seen this. Maybe my official test will have better results. The procedure doesn't look very complicated, although certainly potentially dangerous.

I did notice something strange to me. I turn the crank with a ratchet, and I'll stop turning, ratchet back, and start again to get to the position I want (i.e. normal ratcheting). And often, as I start turning again, there is a little deadzone between when the crank starts to turn and when the cam starts to turn. You can feel it more than see it. Is that also abnormal? I figure that would be due to 'slop' in the intermediate shaft chain and gears (if I understand right that is chain driven), but maybe that is a factor here.

Thanks
Rock

 

[lotusdriver2001]

The belt drives the cams.

 

[David S]

The v& esprit timing belt tensioning and timing should only be done by a qualified lotus mechanic with the right tensioning tools. My experience resulted I a $54k engine rebuild. The mechanic that undertook the work did not have the correct timing tools specific for the job and it ended up in a disaster and a prolonged court case.

No matter how handy think u are, attempting to guess yr way through this will likely end in the same way.

Sorry for posting bad news like this, but best u hear my experience before proceeding.

 

[David S]

Positioning the crank exactly in the right position is critical to getting accurate, repeatable measurements. You cannot eyeball it close. You should follow the procedure exactly. All positions are as you are sitting in the driver's seat so the passenger side of the car is the right side and the right hand bank of cylinders is also on the right side of the car. Confusion can creep in if you are under the car upside down looking rearward. The right side becomes the left. To do the belts requires some special tools, mostly necessary to position the crank. If you are not going to do it correctly my advice is not to do it. An error will be a lot more costly than having it done by a shop.
David Teitelbaum

Double agree with this.

 

[Eric Rogers]

The v& esprit timing belt tensioning and timing should only be done by a qualified lotus mechanic with the right tensioning tools. My experience resulted I a $54k engine rebuild. The mechanic that undertook the work did not have the correct timing tools specific for the job and it ended up in a disaster and a prolonged court case.

No matter how handy think u are, attempting to guess yr way through this will likely end in the same way.

Sorry for posting bad news like this, but best u hear my experience before proceeding.

It's just a matter of being able to follow instructions and rent the correct tools. Not rocket science. Most hack mechanics don't work on quirky Lotuses day to day to know how Lotus did things, and they can't be bothered to read instructions when they only work on them every now and then.

 

[Rock2001]

It does feel a bit skewed toward doom and gloom here. I appreciate all input, but doom talk would be better if I knew what the cause of the doom was so I could avoid it. There is nothing magical in the instructions that I see. I need the crank lock tool and a way to measure the frequency, which I'll have. Although I am trying to avoid any mistakes or bad assumptions because those will be costly, so I'm asking what may sound like stupid questions to ensure I'm not making one of those.

Certainly I understand that the cams are run by the belts, but I believe the cam belt is driven by an intermediate shaft which is chained to the crank, not driven from the crank directly.

 

[irox]

Here's an older thread by a former LT member on V8 belt tensioning.

I have no idea if it's valid or useful, but it is an interesting read:

http://www.lotustalk.com/forums/f164/quick-easy-timing-belt-check-while-still-doing-right-119129/