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Thread: Best way to test a motor that has been sitting for about a year?

  1. #1
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    Best way to test a motor that has been sitting for about a year?

    So I did a compression test on this motor I picked up. It was kind of all over the place. I wasn't sure that cranking the motor over like that would properly lube the rings and obviously the motor is cold. My numbers as started from front to back originally were:
    1- 205
    2-205
    3-180
    4-195
    5-190
    6-150
    I then took a little oil and squirted it down # 6 and it jumped right up to 210. I then put a little oil down all the cylinders to try and keep them lubed while the motor sits. Copression tested then again and they were all 210 except #5 was still 190. So I was thinking about selling this complete motor but I want to make sure 100% that it's perfect before I do. If not I'm just going to build this motor for boost and part out my partially blown motor. What do you think? Should I do a leak down test too? Will that give good enough results on a cold motor??? And no I don't feel like putting it in my car and running it =). I would just build it for my turbo motor. As a side note a member on here sold this motor to someone else about a year ago and said it was a strong motor but gave compression test results of 180 across the board. The person I bought it from never even touched it or started it since he bought it.
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    I was watching a show on some guy who goes around buying up classics, and what I seen him do was spray wd-40 down thru the spark plug holes. Then turn the crank to lube the cylinder walls. Then start the car. Is the motor in the car? Edit: he turned the crank by putting the car in 4th gear then pushed the car abit.
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  3. #3
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    No the motor is not in the car. It's sitting in my garage next to my car, that currently has a half of motor in it. I'm not so worried about keeping it lubed now because I will be making a decision shortly to either sell it or build it. I guess what I'm asking is how to test a cold motor and be sure it's good , or be sure it's not good.
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  4. #4
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    Quote Originally Posted by e36ALPINE View Post
    So I did a compression test on this motor I picked up. It was kind of all over the place. I wasn't sure that cranking the motor over like that would properly lube the rings and obviously the motor is cold. My numbers as started from front to back originally were:
    1- 205
    2-205
    3-180
    4-195
    5-190
    6-150
    I then took a little oil and squirted it down # 6 and it jumped right up to 210. I then put a little oil down all the cylinders to try and keep them lubed while the motor sits. Copression tested then again and they were all 210 except #5 was still 190. So I was thinking about selling this complete motor but I want to make sure 100% that it's perfect before I do. If not I'm just going to build this motor for boost and part out my partially blown motor. What do you think? Should I do a leak down test too? Will that give good enough results on a cold motor??? And no I don't feel like putting it in my car and running it =). I would just build it for my turbo motor. As a side note a member on here sold this motor to someone else about a year ago and said it was a strong motor but gave compression test results of 180 across the board. The person I bought it from never even touched it or started it since he bought it.
    Compression #s will vary according to throttle opening, cranking speed and cylinder lubrication.
    Your engine sat a while so little lube on the cylinders. The #s came up with oil and all the #s are acceptable.
    A leakdown will tell you more but it sounds healthy to me.
    EDIT; Whhops, saw # 6, it deserves investigation. Maybe a ring is a little sticky
    Last edited by ross1; 01-11-2011 at 10:48 AM.

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  5. #5
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    Quote Originally Posted by ross1 View Post
    Compression #s will vary according to throttle opening, cranking speed and cylinder lubrication.
    Your engine sat a while so little lube on the cylinders. The #s came up with oil and all the #s are acceptable.
    A leakdown will tell you more but it sounds healthy to me.
    EDIT; Whhops, saw # 6, it deserves investigation. Maybe a ring is a little sticky
    Yeah, maybe it was stuck but ever since I put a little oil down it's compression numbers are 205-210. I was a little more concerned about #5 that stayed at 190psi?
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  6. #6
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    Can you explain how exactly you did this test with the motor out of the car?

  7. #7
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    I ran jumper wires from another car that was running , to the starter on the motor.
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    Your compression in #6 is very suspicious. If you wanted to use this motor, you could use our ceramic treatment and raise its compression back up probably above 190, the rest of your cylinders I would expect to go at or above 200. It will last you tens of thousands of miles before you need to reapply it.
    We've done numerous compression tests using our treatments with good results. Look at the stats on this page: http://rvsmaster.com/research.html
    In particular, scroll down and look at the tests done by Instyle Auto and Precision Auto Tech.
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    Quote Originally Posted by RVS Master View Post
    Your compression in #6 is very suspicious. If you wanted to use this motor, you could use our ceramic treatment and raise its compression back up probably above 190, the rest of your cylinders I would expect to go at or above 200. It will last you tens of thousands of miles before you need to reapply it.
    We've done numerous compression tests using our treatments with good results. Look at the stats on this page: http://rvsmaster.com/research.html
    In particular, scroll down and look at the tests done by Instyle Auto and Precision Auto Tech.
    Intersting info here;
    however,
    ALL of his numbers are suspect seeing that he did not do his compression testing with a warm/hot engine.

    His #6 rings may have had "shrinkage".

  10. #10
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    If there is no way to tell 100% that the motor is perfect testing it cold then I'm not going to sell it to anyone. I'll just use it myself and part my other motor out. I may try a leakdown test and another compression test , or I may just start taking it apart to go to the machine shop.
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  11. #11
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    Being I had zero (yes zero) compression on all cylinders ,and it leaked 100% on all cylinders. I squirted some oil in the cylinders on my 525, started it and now it has 170 on all cylinders hot or cold. I would say you have not a problem with that motor as far as compression goes. Oh yeah the 525 has 150,000 miles on it. I accidentally washed the cylinders on a cold start flood situation. ///J.T.///
    Lot's of new stuff hope it stays together a little longer. LOL

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