Manager Forum

Car came in with a noise under acceleration. Sounds almost like a heat shield.

I checked all that and found nothing. Pulled oil pan and found a piece of plastic. I knew then it was a piece of the timing chain guide. found passenger bank chain loose. Replaced guides and tensioners. Still have the same noise. Pulled valve covers and I can take my finger and push on the chain and make it get slack.

The tensioner wont tighten it back up. Do I have a bad tensioner? How do these work? I'm guessing oil pressure.

I have run into this already. And, yes, the tensioner is fed by oil pressure. Specs are 20-45 psi at 1500 rpm. Oil must be 5/20 Synthetic. This engine does have oil pressure issues and you could wind up replacing the oil pump as well.

oil pressure is the answer.

I just finished putting in a new oil pump, no change. I found no metal in the oil pan or filter. I did notice that the passenger side tensioner felt like it had oil inside. I had to push real hard on it to get it to release. Driver side felt springy. Just the same as it did when i took it out of the box. I also put compressed air into the ports behind the tensioners. There is a open hole in both heads at the end. SHould it have a plug? I dont know what to do. I even put smoke into the ports. I got equal amounts of smoke out of each lifter. Saw no real difference between each head. I put the "L" tensioner on the drivers side, and the "R" on the passenger side. Only difference I seen was a small hole in the end of the "R" plunger. Oil pressure is good. This car has been here too long. Shopkey gives a vague explanation about a "serviceable" orifice for each head, but does not give a location.

Have you checked actual oil pressure with a live mechanical gauge? At the risk of sounding like I am insulting your intelligence, the oil pressure switch is on the left side of the block, behind the power steering pump as I recall. Thread that out and install a live gauge on a hose (mine is 6 foot long) and watch oil pressure through different engine rpm's. Also, what weight oil is being used?

oil pressure is about the same on both heads, maybe a couple pounds more on the driver side. I checked it at a 1/8 npt plug at the front on the pass rear on driver. Just got done doing that.

I checked it with a 100 psi pressure transducer on my modis. I'm using 5w 20. This engine looks nice inside too. I checked the pressure at varying rpms. especially close while the noise was going on. Right now I have no belt or anything on the engine to interfere.

A previous job is reminding me that these engines also have lifter issues as well. What I am saying is don't rule out the possibility that the noise is lifter related.

Just a thought.

How can I check those? Pull em out and squeeze em? What should I do next?

Well, I have not physically removed lifters strictly for checking them. What I do is use my electronic stethoscope and determine precisly where the noise is coming from. If the loudest noise is coming from the front of the motor then the problem likely is a chain issue of some proportion. If the noise is coming from under the rocker covers, then the lifters are the most likely suspect. I simply replace all of them not taking the time to check each one individually. Oh diagnosis takes time, I know but with the cost and complexity of today's drivetrains, ya gotta know with precision what's going on and where the fault is.

just a passing thought here. a cracked flywheel will make such a noise that can and will travel through the crank and sound like it's coming from the front of the engine.

steven kiser wrote:just a passing thought here. a cracked flywheel will make such a noise that can and will travel through the crank and sound like it's coming from the front of the engine.

Oh yes. Hadn't thought of that. I have also seen that.

Already had the transmission out and looked at that too. I'm gonna go to the salvage yard and get some valve covers and cut out the front where I can watch and listen to the chains to make sure that is the problem. It's really hard to tell where the noise is coming from. I do not have an electronic stethoscope. ALways wondered if they really worked.

protraxrptr17 wrote:. ALways wondered if they really worked.

I would not be without mine now that I have had it several years already. My hearing is only 40% and in a situation where noise is coming from - the electronic stethescope is the tool of choice.

just tracked down my snap on guy and got the blue point. Just a quick check at idle i can hear a definite louder noise on the pass side part of the cover. Waitin on my worker to finish something so he can put the engine under a load. This stethoscope really does work.

i didnt even know they have an electronic one, have a regular stethascope, seems to work well in identifying noises

I was a bit skeptical before I got mine but now that I have it .......... my other one collects the floating dust here in the shop. With mine I can hear current jumping inside a cracked spark plug. It is definitely one of the best tool purchases I have ever made.

protraxrptr17 wrote:oil pressure is about the same on both heads, maybe a couple pounds more on the driver side. I checked it at a 1/8 npt plug at the front on the pass rear on driver. Just got done doing that.

What pressures did you read at idle & 2000 rpms?

about 70 at idle 80 at 2000 rpm. thats engine cold.

Well, based on those oil pressure figures, I'd be forced to conclude the problem is elsewhere. If there is definite noise under a particular section of rocker cover, I'd likely pursue that. keep in mind that in these bi-metallic engines, noise can travel and fool the tech. Been there done that. And those hollow camshafts on the 4.6L and the 5.4L engines - noise really resonates through them.