I have a problem with my 2003 LS. 84,000 miles. When the engine is warmed to run condition, the enine has a very loud knock above 2100 RPM. I first thought it was the oil control valve for the VVT so I bought a new one. The CEL ( 0012) stopped coming on, but still the noise. I changed the VVT unit, did a complete belt, water pump and all seals. NO change ! I understand that a PCM condition (and replacement by Mazda) is in effect. I run 5W-30 syn. oil. Could this really be a PCM problem ?
Jasper
The first problem is to determine where the noise is coming from. Head area or lower block area. A mechanics stethoscope may be of help.
An actual oil pressure reading (Not fun to do) may also be of some limited help. I have a 99, and have used full synthetic oil (10W30) for years. The mileage is about 89,000, and the engine has been turbo'd for about 60,000. Minimal oil usage, and due to the turbo, oil changes are usually frequent.
Well, the noise sounds like the VVT area ( with a stethoscope ) and I was using 10W-30 dino oil but switched to see if it would change anything. Scoping anyplace else is not loud. I do have a real oil pressure gauage in the engine compartment. 75 lb on start up. about 25 lb at hot idle. At 2000 RPM, 30lb +. If I drive around under 2000 RPM all warmed up, no noise! If I add a little power or load the engine on a hill, the noise goes away until the power unloads. Kind'a like a "rod knock". If it were a connecting rod, it would have come out thru the block by now! (over a year now) and I have turned it 7,000 + for a time and nothing changes and the loise keeps up with ith RPM and no louder. I have removed the other belts and no change.
Jasper
VVT Noise The VVT rotating assembly on the end of the cam may be the culprit. Seems that there is a pin assembly that can cause noise. (Service Bulletin, etc.) I'd attach a picture, but my news server is not accepting attachments for this group.
On 6/28/2010 10:33 PM, jasper wrote:
Jasper
Sounds to me that you will need to really determine exactly where the noise is the strongest. On an engine without plug wells, I'd pull the valve cover and run the engine. Not so easy to do on a Miata. Not having a VVT, I don't know what the Gotchas might be.
So the dealer hasn't a clue either. That's not too unusual, since dealers usually replace engines rather than repair them.
Well I took the car in and had Mazda do a complete check on the engine. $56.29. OK price for me. PCM is good and has the latest updates. The noise is from the inside of the engine. Rod bearing or broken piston. Eather way, it looks like I will need a new short block. I'm just getting too old for this kind of crap. It is easier to pull the engine and drop the pan to check the rods and pistons. I have all the things to do it, just too old and with handycaps. If it is a rod, it will mean a crank and a piston will need a bore job and pistons + rings. Used short block is easier. Not too expensive, cheaper than a rework.
Jasper
Have something to add? Share your thoughts — no account required.
Ask the community — no account required