Author Topic: Can a M42 motor come out of time? (Read 23587 times)

RED IS 91 · « **Reply #60 on:** January 21, 2009, 03:52:48 AM »

Thank you Peerless .Great explanation.

peerless · « **Reply #61 on:** January 21, 2009, 01:06:29 PM »

Quote from: rallyegolf;65075

Thank you guys for clearing that up for me. I was obviously doing the leak down test incorrect. I guess to do it the right way, I need to find out how I figure out TDC on the compression stroke of each cylinder.

If I get the motor to "true" TDC, then is that the compression stroke on piston #1? After that, I just figure out the firing order and turn the crank to the next piston at TDC that is the next to fire. Does that make sense?

Quote

I think a more conclusive test here would have been a simple compression test. Typically in diagnosing something of this nature a compression test is done first. After it is determined that a loss of compression is present, THEN you do a leak down to pin point it.

Do a compression test first, if the numbers come up low, then you do a leakdown test.

rallyegolf · « **Reply #62 on:** January 21, 2009, 06:24:41 PM »

well my compression test came out at 120-130 per cylinder. This is with a cold engine of course.

KenC · « **Reply #63 on:** January 21, 2009, 06:43:45 PM »

It's really hard to tell if the numbers are good with a cold engine. At least they're consistent. How many times did you let it crank over?

rallyegolf · « **Reply #64 on:** January 21, 2009, 07:13:17 PM »

5-6 times.

peerless · « **Reply #65 on:** January 21, 2009, 07:49:50 PM »

The point being, if the engine was out of time, you would bend a valve. Therefore you would not have good compression cold or not.

You have good compression, the engine is in time, so move on.

Back to the Fuel Pressure Regulator and/or further testing.

You only need 3 things to make a engine run......Fuel, Spark, Compression.

What you do know is you have compression, I assume you checked for spark, and you know your fuel pressure is excessively high. So go with what you know, there is a problem with fuel pressure, correct the problem and move on.

colin86325 · « **Reply #66 on:** January 21, 2009, 09:18:39 PM »

Good posts by Peerless.

Did you hold the throttle all the way open when you did your compression tests? Failing to do so could result in low numbers. But this is not your problem--I was just curious.

KenC · « **Reply #67 on:** January 21, 2009, 09:36:47 PM »

Quote from: peerless;65145

The point being, if the engine was out of time, you would bend a valve. Therefore you would not have good compression cold or not.

You have good compression, the engine is in time, so move on.

Back to the Fuel Pressure Regulator and/or further testing.

You only need 3 things to make a engine run......Fuel, Spark, Compression.

What you do know is you have compression, I assume you checked for spark, and you know your fuel pressure is excessively high. So go with what you know, there is a problem with fuel pressure, correct the problem and move on.

Word. Replace the FPR.

rallyegolf · « **Reply #68 on:** January 22, 2009, 05:33:57 PM »

is this correct? FPR part # 13531721992 $110.00

??

wow

KenC · « **Reply #69 on:** January 22, 2009, 06:10:11 PM »

That's the right part number. I bought mine for like $6X from BMA I believe.

RED IS 91 · « **Reply #70 on:** January 23, 2009, 04:02:41 AM »

1991 m42 $68.47

http://www.autohausaz.com/search/product.aspx?sid=xtdfcyegbh3owg55p11osj55&makeid=800003@BMW&modelid=1011249@318I&year=1991&cid=22@Fuel%20%26%20Air%20System&gid=6124@Fuel%20Pressure%20Regulator

rallyegolf · « **Reply #71 on:** January 23, 2009, 07:15:13 PM »

I would hate to buy this thing to find out mine works fine. I don't really know how to tell though until i buy it.

roundel318 · « **Reply #72 on:** January 24, 2009, 09:48:28 AM »

It sounds cheaper than a rebuild, try it

peerless · « **Reply #73 on:** January 24, 2009, 12:46:27 PM »

Quote from: rallyegolf;65266

I would hate to buy this thing to find out mine works fine. I don't really know how to tell though until i buy it.

Did you or did you not do a fuel pressure test?

If your not sure then you better do the test again.

Do you have a pinched return line?, you will have to inspect it all the way back to the tank.

If your not sure, you have to make sure.

rallyegolf · « **Reply #74 on:** January 26, 2009, 05:36:17 PM »

I had to take a weekend off to play, so I have no updates so far. This week I will track the fuel through its travels. I will see if we have any blockage, kinks, or leaks.