944 2.5 Lux engine rattle on cold start

jonjeffryes · 09-18-2007, 05:15 AM

Hi guys, this is my first post so thanks in advance for the help.

My car is a 1984 UK model 944 2.5 lux with a manual box and 52,000 miles on the odometer (believed to be original) with the rest of the car condition seeming to confirm the low miles.

My UK model 1984 2.5 Lux has developed a rattle from cold. It seems to be coming from the front of the engine and goes quickly as the engine warms. It sounds similar to the noise a loose heat shield would make.

After the cold start, the noise goes and stays away even on subsequent start ups, until the next dead cold start (i.e. the next day).

The car has a good service history and belts etc were changed c. 5000 miles ago.

Oil and filter were changed just over a 1000 miles ago (10w40 synthetic).

It may be coincidental, but I've gone to start the car yesterday and the clutch pedal has hit the floor and stayed there...looks like the slave cylinder has died!.

Any advice would be gratefully accepted.

Regards

Jon

TNT25169 · 09-18-2007, 05:56 AM

Looking for another set of opinions from a different group?

legion · 09-18-2007, 06:24 AM

My car makes the same noise. I've been unable to track it down as it will only make the noise when the car is in motion.

jonjeffryes · 09-18-2007, 06:59 AM

Quote:

Originally Posted by TNT25169

Looking for another set of opinions from a different group?

Called my parts supplier to order the parts and his suggestion was to go for a second view... In view of the cost (£300+) I guessed it would be a good move

Regards

Jon

TNT25169 · 09-18-2007, 07:22 AM

I've been getting the emails from the yahoo group all weekend and although my car doesn't make those noises, it does have me thinking a little bit.

CJFusco · CJFusco's Garage

You guys are confusing me. What was the original diagnosis?

TNT25169 · 09-18-2007, 08:02 AM

"I strongly suspect it is your valve seals. There is absolutely no heat shield that will make such a noise. If your head has never been rebuilt-then consider it due. A snapped valve will demolish your engine completely. It happened to me.....twice already! Have it checked ASAP. The reason I know it is your valve seals, is because you said the noise went away as the engine got warmer. If you keep driving it- you will soon see smoke come out of the exhaust, when accelerating hard. That is a tell-tale sign, my friend. One day, the engine will just quit on you and a huge black cloud of smoke will billow out of the pipe. By then, it is too late. Upon closer examination- the damage is extensive. A shattered piston will result, and the collateral damage will render the head and block completely useless(exploded cylinder wall, and cracked head). Not a pretty sight, and a complete pain in the arse to clean up."

Copied from an email.

nynor · 09-18-2007, 08:29 AM

loose timing/balance belt slapping. as the engine warms, things tighten up. i bet if you take the top belt cover off, it will be covered with belt dust from damage to the belt and there will be slack in one or both belts.

jonjeffryes · 09-18-2007, 11:39 AM

Quote:

Originally Posted by nynor

loose timing/balance belt slapping. as the engine warms, things tighten up. i bet if you take the top belt cover off, it will be covered with belt dust from damage to the belt and there will be slack in one or both belts.

I'll pull the covers tomorrow evening (GMT times) and report back. I should add the noise has only recently started and really does sound like a heat shield or similar vibrating.

I've no problems with spending the money to get it right...just want to make sure I'm spending it on the right bits!

BTW, I've pulled the plugs and all are evenly coloured with no real oiling evident.

Regards

Jon

nynor · 09-18-2007, 11:46 AM

seven 10mm bolts on the top cover and you'll know if its the belt(s).

nynor · 09-18-2007, 11:48 AM

and welcome to the forum!

jonjeffryes · 09-19-2007, 11:47 AM

Quote:

Originally Posted by nynor

and welcome to the forum!

Thanks, I'm glad to be here

I've pulled the belt cover and surprisingly it's clean inside...However, the balance belt seems to be very loose on the longest run (between the upper balance shaft sprocket and the lower tensioner sprocket. The deflection is 2- 3 cm's - it could be further but is limited by the Water pump pulley and the timing belt tensioner roller!! That don't look right to me!

This weekend (work commitments stop me before then) I'll have a good look and adjust as required and then see if there is any improvement.

Regards

Jon

#391 · 09-19-2007, 01:36 PM

There is a heat shield between the oil filter and the exhaust manifolds. The mounting tabs sometimes break causing the shield to rattle. Perhaps it's rattling when the engine is cold because it's vibrating more, then as the engine warms up and smooths out the vibration lessens and the rattling stops.

It's easy to test anyway....grab on to the heat shield and wiggle it, see if you can duplicate the sound.

jonjeffryes · 09-19-2007, 03:19 PM

Quote:

Originally Posted by #39

There is a heat shield between the oil filter and the exhaust manifolds. The mounting tabs sometimes break causing the shield to rattle. Perhaps it's rattling when the engine is cold because it's vibrating more, then as the engine warms up and smooths out the vibration lessens and the rattling stops.

It's easy to test anyway....grab on to the heat shield and wiggle it, see if you can duplicate the sound.

Thanks,

Just been down to the garage and checked. The shield is absolutely solid - no movement at all so that's another possible cause eliminated at least.

Regards

Jon

DMRK · 09-19-2007, 03:40 PM

Quote:

Originally Posted by jonjeffryes

Thanks, I'm glad to be here

I've pulled the belt cover and surprisingly it's clean inside...However, the balance belt seems to be very loose on the longest run (between the upper balance shaft sprocket and the lower tensioner sprocket. The deflection is 2- 3 cm's - it could be further but is limited by the Water pump pulley and the timing belt tensioner roller!! That don't look right to me!

This weekend (work commitments stop me before then) I'll have a good look and adjust as required and then see if there is any improvement.

Regards

Jon

When adjusted correctly the balance belt will seem too loose.

nynor · 09-19-2007, 05:40 PM

did you rotate the engine to TDC, then back 10 degrees to check the timing belt?

jonjeffryes · 09-20-2007, 11:31 AM

Quote:

Originally Posted by nynor

did you rotate the engine to TDC, then back 10 degrees to check the timing belt?

Yes,

Back roughly 1 1/2 teeth which is about 10 degrees (this was only a quick check)

Regards

Jon

badjones · badjones's Garage

I agree with the belt slap conclusion. When its dead cold take the covers off and start it up. You will see the belt deflection and where it is hitting as well. Sounds like a heat shield or something but its not.

924Sman · 09-21-2007, 06:22 AM

Just to throw in another possibility to consider....If the car has sat for a good deal of time the lifters will drain out and air takes it's place. It can take up to 1/2 hour for the oil pressure to pump them back up. And if bad they will leak after a short time. This could be why you hear nothing then a day or 2 later back to the noise.

Another....make certain the tensioner pulley is on correctly( flange to the block) and the correct size of pulleys, and S has a wider one iirc and ez to mistake.

Dal

ronin · 09-21-2007, 12:33 PM

Quote:

Originally Posted by 924Sman

Just to throw in another possibility to consider....If the car has sat for a good deal of time the lifters will drain out and air takes it's place. It can take up to 1/2 hour for the oil pressure to pump them back up. And if bad they will leak after a short time. This could be why you hear nothing then a day or 2 later back to the noise.

Another....make certain the tensioner pulley is on correctly( flange to the block) and the correct size of pulleys, and S has a wider one iirc and ez to mistake.

Dal

that's the best answer yet