QuestionQUESTION: I know your expertise is in Civics, but I figure this is more of a universal problem. I've got a 1990 Honda Accord EX, and when I start it up, I've got around 4o psi @ 1000rpms and 60 psi @ 2000 rpms. At operating temp, I've got 0 psi @ idle, and about 25 psi @ 2000 rpms. I'm no mechanic (aspiring to be one though, and an avid DIYer), and even I know 0 psi is bad. Could you possibly tell me whats going on? I've just replaced the main and connecting rod bearings (standard size), a mechanic told me they might need 0.001 over-sized to compensate for wear. Is this true? I've also done some research, and it seems there is another possible problem having to do with a relief valve in the oil pump. If you could give me your thoughts and advice, I would greatly appriciate it. (P.S. The car is parked until I find and fix the problem.)
ANSWER: Saul, 0 psi at idle is scary. Do not drive the car until you figure this out. At the bottom of the oil pan internally is a pick up (with a screen) that feeds the oil pump. I would replace the whole unit. Have you checked compression ratio's across the top of the head? This will help you find out whether or not your refreshed bottom end is performing correctly. These motors don't wear a lot unless they have been abused and have had a lack of maintenance. Start there and if you need anymore advice on which areas to check further give me a follow up.
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QUESTION: How would I perform this compression test (I'm assuming cylinder compression)? And what do I look for to know if it's working properly? Would I be able to tell the difference between cylinder ring wear and improperly sized bearings? As for the abuse, I bought the car off of craigslist, and I am not sure of the abuse it has taken before our ownership (I doubt they did much, it needed shocks badly and the tires were worn beyond all belief, and a blown head gasket [no antifreeze in oil or vice versa though], among other things). It all started when our car began to leak gallons of oil, but I couldn't find out where it was coming from. Then the oil light began to flicker (even when topped up on oil) at idle, and if it was on long enough, the light would flash constantly. I figured until I found the problem, I would just keep the rpms up. We were driving down the freeway one night when I heard-THE NOISE. It ruined my day, because it had happened to my beloved truck a few years back (seized the engine). The #3 connecting rod bearing had spun, so as soon as I heard THE NOISE, I pulled over and had the car towed home. Replaced the bearings (rods and mains, and luckily I pulled over soon enough to save my car from the junkyard), and the oil light is still on. So I haven't the foggiest idea as to what to do now, I looked at the oil pickup tube and other than a few pieces of bearing (nothing was wrong with the crankshaft, all smooth and shiny, much to my surprise), it was very clean. So any other thoughts? I really dont want to replace my brand new bearings with different ones (and I really can't afford it either), but if I have to, I will.
ANSWER: Saul, the compression test is done by removing a spark plug and threading in a cylinder compression test tool. Which you can pick up from any local auto parts supplier. Cylinder compression should be between 140 to 180 per cylinder. But, for exact specs consult the internet under cylinder compression ratios per year, make, and model. Start there!
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QUESTION: How does this tell me if my "refreshed bottom end is performing correctly"?
AnswerYour rings are the sealing point for which compression is compounded in the stroke of the crank to the head. Adding fuel and spark in that chamber creates an explosion thus the compression engine is created. "I've just replaced the main and connecting rod bearings (standard size)," - since you have performed this service to the bottom end you need to check that each cylinder is getting the proper compression. This is basic mechanical knowledge. If the #1 cylinder is 180, #2 is 175, #3 is 45, and #4 is 180. Then you know that your issue resides in the #3 cylinder area and the rings are bad. Or maybe they are all fine and you can move onto checking other areas of the engine.
