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Discussion Starter #1
I kind of got burned with a CL engine. I have a P0304 code and a rough idle when cold. It runs great once it is warmed up, but I cant pass inspection with the code being thrown. I have already swapped, wires, coil, and injector with no change. Checked compression on cyl 1 and 4 . Cyl 1 was over 200 cold? and around 180 hot. Cyl 4 was around 130 cold and 150 hot. Kind of weird how compression went down in cyl 1 and up in cyl 4, but either way cyl 4 still had significantly lower compression.
 

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I don't think your compression is anything to worry about. It should be measured on a warm engine, so you have 180 and 150 psi on cylinders 1 and 4. No too bad.

When you say you swapped parts, do you mean replaced with new, or just move to different cylinders?

I assume the P0304 code is the only one you are seeing. What is your model year and engine code?
 

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Discussion Starter #3
99 beetle 5sp. I swapped wires with the 1 and 4 cyl still got code p0304. I even replaced the 4 wire with the one form the old engine, same deal. Changed the coil out for the one off the blown engine still p0304. P0304 is the only code that comes up. The reason why I was concerned with cold compression is I read somewhere that AEG is prone to low compression on cold starts when the rings are worn. The car runs rough on cold starts idling and sometimes even after warmed up. Idling only. Has smooth power through acceleration and cruising. The lifters were pretty noisy, so I checked oil pressure and it was over 50 psi at idle. I dont have a leak down tester, but I hooked my compression gauge's hose to my compressor and I can hear air blowing in the crank case. I removed the cam and was not able to squeeze any of the lifters by hand. On the old engine, I was able to squeeze about 6 out of the 8 and get oil to squirt out of the hole. I heard no air coming past the valves with compressor hooked up. Do you think I should throw in a set of lifters and do a re-ring?
 

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I don't think that the compression is causing the problem. On engines with a blown head gasket the compression on one cylinder will be below 50 psi and I don't think it causes misfire codes. I'd try replacing the knock sensor on #4 with one from your donor engine. The misfire is determined by the knock sensor so it could be a bad sensor.

I'm concerned that your oil pressure at idle is too high. It could mean that the oil passages are plugged, especially since you mention the lifters. If oil is flowing properly the pressure should be quite a bit lower at idle than at higher rpm.

I'd check the compression on all four cylinders after the engine is thoroughly warmed and base the decision to rebuild on that. How many miles do you have?
 

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Discussion Starter #5
I was told it had 120k. The car itself has 109k. That oil pressure is with me adding visoline ring repair. The stuff was thick and didn't help at all with compression.
 

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Discussion Starter #6 (Edited)
Update:rering

I went ahead and did a rering. Now she runs smooth whether warm or cold. Sorry for lack of pics, but I took what I could with my phone. Stopping to take off gloves and/or wash hands to take pics was not in the schedule and my wife wanted nothing to do with the project. I don't blame her though. If anyone has any questions specifically about what I did, let me know.

Had to bless the engine (or the guy who sold me it). At least it was repairable:mad:

I checked the oil pressure because valves were annoyingly noisy and I wanted to make sure the pump was healthy before continuing on. This is where to screw in the gauge. The shiny brass fitting is from my oil pressure gauge. There is a plug that has to be unscrewed first.

I took the intake manifold off without splitting the plenum. It's easy enough, just use a pick to unplug the injectors. Then slide the harness out toward the driver's side.

I removed oil pan, oil pump, and plastic baffle to expose con-rod bolts. I was sure to keep pistons located in reference to which cylinder they came from.

I removed and cleaned valves and cylinder head along with the pistons. Lapped the valves before reinstalling. I noticed cyl 2 and 3 had significantly more carbon build up than 1 and 4. Lazy mechanic left those plugs in and changed the ones easily accessible?

Deglazed the cylinders with honing stones. VW recommends monkey balls, but I already had the stones.

Removed old rings and cleaned the grooves. Installed and clocked rings 120 degrees before installing pistons.I reassembled the head with new seals and lifters, replaced con-rod bolts (TTY bolts and I'm not jeopardizing the engine to save 40 bucks, replaced con-rod bearings (old ones were not bad, but might as well). I installed the head with new head gasket and bolts(TTY bolts also). The car runs great now. Super smooth idle and best of all, no more p0304!
 
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