Cambelt replacement

[andyblackman777]

Im currently replacing the belts on my 96 V8. There is more room than I thought so removal of all necessary parts has been quite straight forward by just laying on top of the engine. 👍

My only problem so far is that my Crankshaft pulley has no markings against any of the 4 vanes? One vane did have some evidence of possibly some yellow paint on it. 

Anyway I locked the crank at all vane positions and the tolerance pins only went in at one position. On the 2nd go around I might add, starting at the 'yellow' vane.

Im assuming that the pins only go in at one position 10 deg BTDC (firing) No2 Cylinder.  Does anyone know if this is correct?  Im pretty sure but want to double check before continuing.

Cheers

Andy

 

[mike_sekinger]

Yes.  The camshaft drillings are all made with that one reference to 10deg BTDC #2 cylinder (firing).

The TV Damper should have a marking on the side corresondining to that.  It may have been missing on very early cars, but I can#t say that I've seen one without it.

Note: that the crank needs to be turned twice for one complete revolution of the engine (half-speed idler)

[andyblackman777]

Definitely no mark?

The other engine I have  is marked as in your picture.

I read that some early engines have two drillings of the camshafts one at 10deg BTDC #2 cylinder and the other at 10deg BTDC #1 cylinder!

I did two rotations and the pins only went in once out of the 8 options!!

[mike_sekinger]

Then you have your answer 🙂

Now you know the reference point, make your crank position pointer and you are on your way.

[andyblackman777]

Thanks Mike. 
I found some time this morning to replace the belts. I did another check of the timing position, the pins only go in one time out of eight possible positions. My unmarked pulley/ damper is now marked!

Belts are replaced now and timing still good after 2 rotations of the crank. I just have to check and adjust the tension now. A bit fed up of turning the crank over so I’ll do it another day. Belt tensioner and  idler pulley bearings are good. Auxiliary belt tensioner pulley is a bit wobbly so will order a new one. (30,000 miles).

For anyone doing this job the hardest thing is probably turning the crank over. Maybe combine it with a spark plug change😂

Also, buy the timing pins and crank locking tool. I wouldn’t mess around with drill bits. With the proper pins you know when they’ve gone in properly. Well worth the money £130 from PNM. I made a tensioning tool. 
 

[mike_sekinger]

Good stuff.  It's definately not a job to rush.

I dug out the images showing the comparison between the Clavis and the software app.   I remember that I did source a decent low frequency microphone for this.

[andyblackman777]

Thanks Mike. I wonder why the clavis gauges are so expensive I have £20 guitar tuner which is obviously bang on. I guess the proper automotive gauges are lot more robust and no so much in demand.

Anyway, I got round to tensioning the belts today. It took 3 or 4 goes, just a case of getting to know what is needed adjustment wise. Again turning the crank twice every time is a pain with the engine in the car. I found his easier from underneath. 

I have one question, after adjusting the tension and then rotating the crank twice to get it back to the correct checking position I get 130Hz. If I then give the belt a twist/pull it reads a lower amount, say 100Hz. If the crank is then rotated a further 2 times were back to 130HZ. I'm assuming that the belt tension is checked while in tension from the said rotations, not in a "relaxed" state. In the same position. ?

 

 

 

[mike_sekinger]

Yes, agreed turning the engine from underneath is easier.  Popping up and down is a bit tedious. I've experienced dependable readings with changes but manually playing with the belt will affect the frequency reading.

The tensioning positions and values for new belts were re-specified in a Service Bulletin in mid-1999.

[andyblackman777]

Thanks Mike, the above is exactly what I did. Got 125 and 130hz (Lotus belts)and the same again after rechecking.  👍 

Might just do one more check just to be sure😉. Waiting for some parts now anyways. 
 

 

[andyblackman777]

So I tripled checked the tension. I got 122 Hz on the left bank and decided to try to match it to the 130Hz I have on the right bank. Suppose to be 120-135Hz on new belts. Anyway I spent ages adjusting it and settled back on 122 in the end! It’s tricky adjusting the tension and tightening the bolt. I’ve gained plenty of experience of what’s required to increase or decrease tension. 
I don’t know why I didn’t do it myself before. 

The car starts and runs at idle. I haven’t road tested it because I’m waiting for a new auxiliary belt and pulley. 

For anyone planning to do this job the adjustment of the tensioner is tricky and turning the crank is a bit hard work. Not difficult just tricky because of access. It would be very straightforward with the engine out of the car.  
 

I did notice that center section of the plastic belt covers has split where the metal tubes are inserted , these are where the retaining bolts go through. The metal tubes have corroded and split the plastic. Which is a shame. I have another one and that is similar, not quite as bad. I’ll probably replace it next time. Unless I find a way to repair it in the next 4 years 😂

 

[cweeden]

Hi All,

I've been reading the notes on setting the timing and the following paragraph leads me to believe that when the camshafts have their setting pins in place the valves must all be in a safe position where no piston can hit them. Is that true or am I going mad?

With the camshafts still locked, turn the crankshaft clockwise, dragging the cam pulleys just until the
crankshaft positioning tool TO0011339 can be inserted through the sensor plinth to engage fully with the
marked vane on the crankshaft pulley (timing disc will read 10” BTDC No.2 cylinder). If the crankshaft is
inadvertently turned too far, do NOT reverse direction, but continue clockwise for a complete revolution.

cheers

-Chris

[ramjet]

That is what I understand from that as well @cweeden. I would think that the instruction on not turning backwards would be to eliminate backlash in the engine valve train.

Hopefully @mike_sekinger will see this and reply. He is a plethora of information on the V8.

[jonwat]

12 hours ago, cweeden said:

If the crankshaft is
inadvertently turned too far, do NOT reverse direction, but continue clockwise for a complete revolution.

If any the valves were open enough to contact their piston(s) this instruction would do just that. 

[cweeden]

2 hours ago, jonwat said:

If any the valves were open enough to contact their piston(s) this instruction would do just that. 

that is how I read it too but I wanted a sanity check since it's quite a leap of faith after the time and effort of a rebuild to rotate the bottom end while the top end is static. I have visions of spoof moments in films where the slighted touch is exaggerated into a huge explosion translating to a piston kissing a valve and launching the whole cylinder head into orbit. 🤣

[jonwat]

10 minutes ago, cweeden said:

I have visions of spoof moments in films where the slighted touch is exaggerated into a huge explosion translating to a piston kissing a valve and launching the whole cylinder head into orbit. 🤣

I did when changing the camshaft bearings on my Europa twin cam head, I'd slackened off the chain adjuster & didn't realise the chain would be hanging loose from the crank sprocket when I turned her over. 

Was also at a car show & looking at the Lotus stand there was a brand new 900 series piston, perfect in every way except for the two valves sticking out of the top of it. 

[mike_sekinger]

The crank should be put in the safe position 45deg BTDC #2 cylinder, prior to positioning and setting the cam locating pins.  This then allows for the timing belt slack to be evened out while turning to the 10deg BTDC reference point.  Personally, I would never turn the crank fully while the cams are set at 10deg BTDC.

There is an alternative technique for removing the timing belt slack by using the tensioner itself.  Again leaving the cam pulleys loose, you can apply a reasonable tension on the each timing belt to even out the belt runs.

[ramjet]

I actually just thought about my previous post.

Valve train backlash. It's driven by belts Michael, ya idiot. (Not Mike S. Me.  )

[cweeden]

It strikes me that there is a safe position for the crank and also a safe position for the cams.

At 45deg BTDC #2 is the crank safe position where you can do what you like with the cams and valves.

With the cams locked with setting pins, you seem to be safe to do what you like with the crank and pistons (according to the text in the manual).

Thanks for the feedback.

cheers

-Chris

[Tim H]

Can anyone tell me where does the crank sensor connector wiring go to, I thought my sensor had gone due to not starting no fuel / spark, I have moved the wiring slightly / checking the connection on the crank sensor and the car started so I think the wire has a bad connection broke within the wire so it needs replacing and I wish to replace the whole length.

Thanks for the advice , appreciated....

[mike_sekinger]

The crank sensor wires runs as part of the main engine loom back to the ECU connector (pin 79 SigGND, 73 RefHI).

You probably won't want to unpack the entire loom, but could run a replacement pair externally if needed.  I would buzz the pair and see if you have a weak connection first.

[Tim H]

Thanks Mike appreciated.....

[Tim H]

I am surprised how thin the wires are compared to other crank sensors on the other cars I have... and they have no insulation around them either like the others.... also I think the same for the oil temp sensor on the sump plug....