Sounds like timing chains scraping, but I am not sure now...

[bunni]

I've had my D for about 6 months now, 3rd owner, previous owner used it as a daily driver. When I got it it had a few leaks, a few noises, electrical problems (duh), and so on. What I am looking at tackling right now is (or so I thought) the timing chains. I can hear what sounds like a mildly high frequency of something being dragged on something else, the frequency increases with higher RPMs. Myself and a few others had thought this was the timing chain, so I ripped off the cover and saw nothing scraping where it shouldn't be. I have never really heard a "good" DeLorean (has anyone? heh) so I am not sure if that is normal or if the noise is coming from elsewhere else. It sound almost like the right side of the engine (when looking at it from behind) while another friend said it sounds like its coming from both sides. Now I imagine that with the metal chain and the metal guides there should be some noise coming from the engine, but I can clearly hear it while driving even, and that has me somewhat worried. Note that I can hear that as well as what I believe are the lifters as well at a different frequency, the noise I am worried about is more continuous and much higher frequency.

Either way I plan on replacing the chains, but I am curious if this is something I should keep investigating.

-Kris

[DMC5180]

Auto or Manual T ? Do you have a way of recording a sound clip and posting to hear. I HAD a mysterious sound like that many years ago. I never determined what it was. It went away on its own. The howling sound came from the Coil cover area of the engine compartment. It almost sounded like a dry bearing howl. Or possibly a Vacuum leak whistle of some kind. Btw: The main Vacuum port from the engine is on that side at the back of the right Intake Rail. It should be easy to check for a loose hose clamp or a split hose. I recall once when I was trying to determine the source, I pulled the Crank case vent hose off the Air cleaner and Plugged the Hose with my thumb. The back pressure would cause the howling sound to appear. If I released it , it faded away after a few seconds. I also used to hear the sound if I started the car first thing on a cool morning. It would go away as the engine warmed up. I haven't heard the sound in a few years now. I may have fixed it unknowingly when working on other things over the years. I do recall it was a harsh sound and I've always had concern when I would hear it.

[bunni]

Its a manual. When I get it all back together I can rig something up to record it with a stethoscope or something; right now the cover is half bolted on and I don't have a new gasket. It is definitely not a howl, it is a very mechanical noise. I will post back sometime next weekend with more details and a sound clip if it is needed still. Anyone have any other thoughts?

-Kris

[Bitsyncmaster]

Also check your pulley "idler" bearing. That has been known to make noise.

Use a large screw driver as a stethoscope. Place metal end around engine components and hold handle end on your ear.

[DMC5180]

The other way to isolate the idler possibility, leave the A/C belt off. If you still get the sound it's not them. Not to say they couldn't be bad at some level. What you described doesn't sound like it would be the idler though.

[dhaney]

Also check your pulley "idler" bearing. That has been known to make noise.

Use a large screw driver as a stethoscope. Place metal end around engine components and hold handle end on your ear.

I am betting Bitsynchmaster has the answer "idler bearings".

Dan

[outatym2001]

Here is my shot in the dark since I don’t know what your problem could be.
I helped a fellow DeLorean owner determine one of his two idler bearings is going bad that spin with A/C belt. I used my Sears stethascope with the metal rod attached and listened to the pulley wheel.
You can get the bearings at Napa Auto Parts part number 62022RSJ. About $17.49 each.
You will however have to press out the old ones and press in the new ones.
http://www.napaonline.com/

A stethascope is very handy at helping identify mysterious noises. I used it on my DeLorean and figured out the bearing inside my coolant pump was going bad by simply touching the pump housing and listening. The noise would get progressively louder as the coolant heated up. I knew it was time to take it to DMC Northwest before I would soon start loosing coolant through the weep hole at the underside of the pump shaft.

You sound much more mechanically inclined than myself and don’t forget to let us know what you find out.

[Rich]

Ditto on the A/C idler pulley(s) being a likely source. Take the A/C belt off - you can spin the pulleys and see how smoothly they spin. As already noted, you can then run the engine for a few minutes and verify that the noise stopped.

No amount of lube will fix it. It's a common problem after 25yrs.

Photo here of the Hervey plug-and-play A/C pulley renewal offer. Bearing renewal via press-out and press-in is a previously-noted option.

Am sure your favorite DMC vendor can help once you see if this is the source of the noise and which approach you want to take.

BTW, if you have the A/C belt off it's a good time to replace it if it is >4yrs old.

Link to the Hervey page where the photo came from:
http://www.specialtauto.com/delorean-parts/AC-Cooling.html

2731

[jmettee]

Could also be a bearing in the alternator, especially if it sounds like the right side of the engine. If the engine is COLD, you can the engine without the alternator/waterpump pulley, but I would do it no longer than 30 seconds. Also, spin the alternator by hand & see if it feels smooth or not.

[Bitsyncmaster]

Could also be a bearing in the alternator, especially if it sounds like the right side of the engine. If the engine is COLD, you can the engine without the alternator/waterpump pulley, but I would do it no longer than 30 seconds. Also, spin the alternator by hand & see if it feels smooth or not.

Agreed. Had a friend complain of alternator noise but I never heard it. But spinning the alternator without the belt on it I knew it was bad. It should spin very easy with no vibration or effort.

[bunni]

Alternator runs smooth, I actually just pulled and tested it a few days before (battery light flicker and voltage meter droops while at highway speeds) and it tested fine and made no noise on the bench.

-Kris

[DMC5180]

Could also be a bearing in the alternator, especially if it sounds like the right side of the engine. If the engine is COLD, you can the engine without the alternator/waterpump pulley, but I would do it no longer than 30 seconds. Also, spin the alternator by hand & see if it feels smooth or not.

Yes this is a good test also. I was going to mention it too as an option. I think from the Original description that it is more like the sound I used to experience. Dave S. once told me he had a car do this. I don't recall what he determined it was.

Btw: If the engine sounds like it's scraping metal internally, Its a good idea to pull the Oil Filter. Cut it open and inspect the Paper element for metal . This is normal inspection practice in the Aviation industry. You want to know if there is premature wear happening. The most common on a Gen. Aviation piston Engine is CAM lifter spalling. (chipped or pitted surface of the lifter)

[bunni]

Btw: If the engine sounds like it's scraping metal internally, Its a good idea to pull the Oil Filter. Cut it open and inspect the Paper element for metal . This is normal inspection practice in the Aviation industry. You want to know if there is premature wear happening. The most common on a Gen. Aviation piston Engine is CAM lifter spalling. (chipped or pitted surface of the lifter)

Genius!

-Kris

[David T]

Assuming the motor has decent oil pressure, and no one ever ran it very low on oil, it is unlikely there is a problem with the timing chains. As previously posted you should rule out all of the easy external stuff. Make sure the fan on the alternator isn't hitting anywhere and there are no exhaust leaks. You can run the motor for a short period of time without the belts to rule out an accessory noise. Maybe change the oil and filter too if you don't know what kind of oil in inside or when it was last changed. If there is any question about the health of the motor, before you tear it down you should do a compression and leak-down test. Also hook up an accurate mechanical oil pressure gauge. Check the plastic screen inside the oil filler neck to see if the motor was ever seriously overheated. If the noise IS the timing chains you will probably have even bigger surprises once you open it up. Another possibility is a very misadjusted valve. If you can't find the source of the noise try adjusting the valves before ripping the motor all apart.
David Teitelbaum