Escort Sigma 1600 Race Car

[Roadsport]

Re: It's a loud boy !!

Worked on the car yesterday. Got everything back together and and installed the new air box. Everything went smoothly the box fitted nicely alltough was a nightmare to install. Everything went smootly untill we started engine that is.
The same worrying whining sound why I decided change the tensioner pulley in the first place was still there!!!
I'm clueless. I've changed the tensioner, wtr pump, alternator belt and the timing belt. I've cheked the belt and pulley alingnements. I loosened up the timing belt to the point I still see safe to see wheter it was too tight and made that sound. Checked the oil pump and the drive belt no sound or rubbing there. I've Driven the engine without the alternator belt. The sound is there no matter what I do. The good news is the new timing belt tensioner does not drive the belt off the pulley.
I'll order up a competition cam belt to see if the valve spring tension and steep ramps of the cams are too much for the OE belt. I'll also try and install the belt even looser to see if it helps. I can borrow a digital belt tension gauge from work
But for now all this equals to another missed roller session, another missed race.

Has anyone got a propper Pinto for sale?
Anyway here's the pics of the airbox fitted. Turned out nice if you don't mind me saying. And the reduction in the induction noise was dramating.
So much for the serviseable engine though.

[Tristan]

Re: It's a loud boy !!

Great to see that box there , I shudder when I see cars running open trumpets . The whining.. could it be the dry sump? Or the alternator?

My project has stalled due to me finishing some friends/customers projects to get some money in! And me and my engine tuner mate taking holidays at different times... And then discovering a valve to bucket clearance issue . Shoulda took up Golf...

[Roadsport]

Re: It's a loud boy !!

I have run the engine without the auxiliary belt eliminating the alternator and the water pump. The whining was still there.
Now the dry sump pump. How could I make sure its not the pump? Dare I run the engine briefly without a oil pump drive belt? I have checked that the drive belt does not scrub and I've listened the pump with a stethoscope and it does not seem to come from the pump.
With the stethoscope the sound seems to be loudest from the tensioner pulley. But the belt could resonate to the the pulley making it seem like the pulley makes the sound.

[Graham]

Re: It's a loud boy !!

Dare I run the engine briefly without a oil pump drive belt?

how about doiing it whilst spinning the pump with a drill

[Roadsport]

Re: It's a loud boy !!

Good point Graham. That would work!
I allready contacted Titans and they offered to check the pump asap if I come to the conclusion that it is the pump that makes the sound.

First ill measure the tightness of the belt. I took a reading of the standard Sigma engine and the gauge reading was 45-47. I'll mesure my belts tightness and lower it down to the original spec. If the sound is not gone I'll try to spin the pump with axiliary power. If theres no improvement I'll try a tougher competition belt as a last resort since that feels to be the most far fetched solution.

If these tricks dont do the job I.... I'll....think of something else.

[Roadsport]

Re: It's a loud boy !!

Used this kind of device to measure the belt tightness.

[Roadsport]

Re: It's a loud boy !!

I loosened the cam belt today again. The result was the sound was gone when the engine was cold but soon started again once the engine was hot. I believe it is the cam belt tensioner making the sound under increased stress when hot.
The belt tightened quite a bit when heating up. I dont dare to loosen it anymore or I'm afraid it'll slip when cold. I can test my theory with the original automatic tensioner. Of course that is not the answer to my problem since the automatic tensioner is unreliable in competition use.
But It'll show me if im on a to something here. Maybe I could use a very stiff semi automatic pulley? This would give under increased pressure and not tighten the belt to the point where the tensioner pulley bearing starts to make a noise. It sound a bit odd to me that a tensioner bearing cant take the tension. We'll see when I'll try the originat item.

[Roadsport]

Re: It's a loud boy !!

OK. So I tried the OE automatic tensioner and the sound was gone. No noticable whining that I heard of.The belt behaved fine all the way up to 7000rpm's too.
I turned the engine off and to my horror I noticed the belt had slipped by half a tooth. The belt got up from its groove and the teeth stood on the tob of the pulleys teeth. It seems no damage has occured yet. I counted four compression strokes to a revolution. So seems ok. Phew... won't be running the engine again with the automatic or even semi automatic trensioner again.

I now ordered the billet version of the cossy pulley and the Piper Cams competition cam belt. If the noise is still there, as I suspect it will, I'll let ït be and ignore it.
I'll just keep my eye on it if it gets worse

[owlscastle]

Re: It's a loud boy !!

If you spin the cam tensioner on its own does it make a noise? Are you sure it is not fouling the backplate or some othe sily thing. I know my pulley was touching a bolt head very slightly, enough to make a horrible noise. It does look bigger daimeter than the normal size.

OK. So I tried the OE automatic tensioner and the sound was gone. No noticable whining that I heard of.The belt behaved fine all the way up to 7000rpm's too.
I turned the engine off and to my horror I noticed the belt had slipped by half a tooth. The belt got up from its groove and the teeth stood on the tob of the pulleys teeth. It seems no damage has occured yet. I counted four compression strokes to a revolution. So seems ok. Phew... won't be running the engine again with the automatic or even semi automatic trensioner again.

I now ordered the billet version of the cossy pulley and the Piper Cams competition cam belt. If the noise is still there, as I suspect it will, I'll let ït be and ignore it.
I'll just keep my eye on it if it gets worse

[Roadsport]

Re: It's a loud boy !!

The audi tensioner was stiff and as good as new no noises what so ever when I spinned it but this cossy one spins almost too well on its own and maybe a tiny noise can be heard from it. Cant really be sure though the sound was so faint.
The original pulley is 62mm in diameter and the cossy and the audi are 72mm.But they aren't touching anything. And the belt is not rubbing against anything anymore. I marked with white paint and it has not rubbed off.

[Tristan]

Re: It's a loud boy !!

I suppose with the engine being all alloy there is greater scope for expansion as it heats , thus changing the belt tension? Maybe that's why Ford used a spring loaded tensioner . When you say it slipped by half a tooth , that's terrifying!

[Roadsport]

Re: It's a loud boy !!

Yes the belt slipping gave me a proper scare too. And I belive you are right on the all alloy engine expanding alot too. Friend of mine had a similar problem with the alloy head Pinto. Only he snapped his cam belt.
I've been told the belt slip is a common problem with the Sunbeam Lotus. They have to turn the engine off with the clutch and high gear.
I rather choose to go with the fixed tensioner and listen to whatever sound it makes. Just need to keep close eye on any sgns of wear in the belt and tensioner bearing. And leave some room to expand in the belt.

[Tristan]

Re: It's a loud boy !!

would it be possible to say put 2 marks on the tensioner , or 2 adjustable stops , so that on Race day morning you run the engine for say 10 mins to warm it in the "tight" setting , then slacken the tensioner to the "loose" setting?

[Tristan]

Re: It's a loud boy !!

Actually that seems full of complication . What do other all alloy engines used in competition use ? Like the alloy blocked BDA , the Honda TypeRs etc ?

[exboyracer]

Re: It's a loud boy !!

The Honda engines use a hydraulic tensioner which (in theory) will expand to increase belt tension but won't contact, but in practice there have been cases of loss of hydraulic failure and belt slippage, so many people have gone to a manual tensioner.