T-RED

After the recent freeze in Texas the 1991 944S2 has developed liter noise, almost like metal to metal. Drove the car about a week before the freeze and did not observed the noise. What happened between the last shut down and startup? Approximately one week between the two. Thanks for any comments on this issue.

sp1990

Did you do the basics and check oil and was antifreeze in cooling system prior to freeze?

harveyf

First, as @sp1990 suggests, confirm that the oil level is not dangerously low. Confirm the oil is not milkshake brown, which would indicate a mix of oil and coolant. Make sure the coolant is a proper mix, with a specific gravity type tester. Cheap to buy or borrow.

Using a short piece of hose as a stethescope, pinpoint the location of the noise on the engine. Not to insult you but listen to the fuel injectors, which make a clicking sound. Lifters are a sharp tapping noise. Listen to the top of the engine (the valve/cam housing cover) and see if the sound is under it. Under it localized or under it along the entire length of the cover i.e. one lifter or all lifters. Make sure the noise isn't coming from somewhere else. I am assuming it makes the noise sitting still, which makes it easy to explore with your hose. Noises can be tricky and sometimes "project".

Does your engine have Variocam? I believe this would be indicated on the valve cover. If it does, listen very carefully with your hose at the front of the valve/cam cover, where the Variocam unit resides. On the side of the valve cover that the inlet manifold attaches to, which would basically be the drivers side front of the valve/cam cover.

There is really nothing about cold weather that should cause the lifters to become noisy. Isolate some things as discussed above and report back. You probably shouldn't drive the car until you get a diagnosis.

500

Good suggestions from harveyf on how/where to check. Being an S2, there is also the chain and tensioner that connects the two cams near the mid point. The tensioner has a plastic wear pad that should be periodically replaced. Not sure if a little piece of the pad breaking could lead to a noise like you are hearing, but it is an area I would be checking. Comprehensive failure of the plastic pad will usually lead to significant damage (e.g., cylinders hitting valves, broken camshaft etc.), so something you may want to update anyway, if it has not been.

Good news is that after doing the listening checks, taking off the valve cover in the 16V cars to visually inspect is very easy.

jeyjey

While a short piece of hose will work, a mechanics stethoscope is cheap, and works even better.

(Mine even works after I bent it in half last year through a true idiot move that we won't go into.)

Jfrahm

It might take 20 minutes for lifters to pump back up, keep the revs down.

TurrFinn

I've experienced loud lifter tick after letting my car sit for more than a week, once its warms up it will more than likely go away.