Author Topic: M42 weaknesses also apply to M44? (Read 4863 times)

johna · « **on:** June 27, 2016, 04:56:28 PM »

I saw this post on a few pages about some of the weaknesses of the M42 engine. I was wondering how much of this also applies to the M44, particularly number 2 and number 4? Does anyone know?

Quote from: peerless

Here is my experience with rebuilding 2 M42's. One took 3 engines to make one good one.

We will start with the factory flaws and how they should be corrected.

1) Stamped steel chain guide. These fracture and break apart. Replace with upgraded dealer part, its a all nylon/plastic construction. You will need one new 45mm long bolt in conjunction with the new guide.

2) Steel oil pressure relief valve, aluminum front cover. The steel valve can seize causing a immediate loss of all oil pressure, good by engine. Replace with updated dealer part, made of nylon/plastic. Make sure you get the spring and spacer as well. The spring is slightly longer so it all a matched assembly. You will most likely want to replace the oil pump rotors, front pump cover and bolts. All of this is about $45.

3) Front chain cover. These are known for leaking profile gasksets. The rail that holds this gasket gets corroded and leaks. Every one notices when it leaks outside the block, but no one notices when it seeps behind the block. This creates a rust cavity potentially damaging the front face of the block. Expect to at a minimum to replace the front cover. If the block is damaged, you can surface the front face to clean up any rust damage. .015" MAX.

4) Main thrust bearing. The factory in all their wisdom decided to only use half a thrust bearing shell. This is not capable of handling the high rpm loads created by the M42. You will find the bearing to be rounded and burnt black. The crankshaft thrust surface must be inspected carefully. On the 2 engines I built one crank was scrap and the other barely within spec. To correct this problem you will want to replace with a full 360* thrust bearing. I do not know if the standard replacement bearings come with 2 halfs. I use the early eta M20 main bearing set and have the lower main caps custom machined so they fit. This not only gives me a full 360* thrust surface, it also gives me a full 360* oil groove for improved oiling to the rod bearings. As a note, I pulled the oil pan on a M42 with 80K miles, it already had thrust bearing material in the pan, along with 4 oil pan bolts.

5) Crank pulley. While the stock crank chain gear does not wear very much a new upgraded part is available from the dealer. It has 2 rubber rings molded into it. This helps keep harmonic vibrations in check. This may help prevent the oil pan bolts from backing out

6) Rod bearings, I use custom Clevite 77 NASCAR performance bearings. This is a upgrade, the stock peices should work just fine as well.

7) lock-tite all your upper oil pan bolts to prevent them from backing out. This is a big problem on the front 6 bolts that surround the gasket for the oil pump pick area of the pan gasket. When these back out and fall into the pan the gasket can push out and you lose oil pressure. See number 5.

Regarding valve guides, they should be fine as they have very little side laoding due to the valve train arrangement. I did not need a cam removal tool either. When loosening and tightening the cam tower bolts, take your time, do it slow and evenly. Remember the camshafts are hollow and can break easily.

If anyone tells you the stock M42 is a great engine, they are pulling your leg or don't know the M42 very well. The stock M42 is very self destructive.

I have pictures to back up every flaw I just described above. Everything I said above comes from direct experience with the M42 engine.

Expect to pay about $2,500+ in parts and machine work to properly rebuild the M42. If you need help/advice along the way just give me shout.

Darky · « **Reply #1 on:** June 28, 2016, 01:32:53 AM »

M44 has the updated pressure relief valve but still only a 270 deg oil grove on the thrust bearing!

Hope this helps Rohan

johna · « **Reply #2 on:** June 28, 2016, 04:24:21 AM »

Quote from: Darky on June 28, 2016, 01:32:53 AM

M44 has the updated pressure relief valve but still only a 270 deg oil grove on the thrust bearing!

Hope this helps Rohan

Thank you for the answer.

How can we improve the thrust bearing issue. Do e just need to fit the M50 parts or is there more to it?

Darky · « **Reply #3 on:** June 29, 2016, 01:29:50 AM »

Nope that will do it m50 parts or any non oem all have the 360 oil grove, like vac metric mechanic etc etc

So I guess it depends on how much abuse the m44 is going to get as to which way your going to do it!

Cheers Rohan

dsm2002 · « **Reply #4 on:** June 29, 2016, 03:54:28 AM »

ACL Performance M42 main bearings include a 360� thrust. Probably cannot get a better set of bearings.

Darky · « **Reply #5 on:** June 30, 2016, 08:28:49 AM »

Interestingly that metric mechanic and xrally parts both use a trimetal bearing. I'm willing to bet they collaborated or one uses the others stuff. Knowing those 2 use that, that was the direction I went. Xrally parts also do titanium valves 145 mm conrods 85mm cranks and s42 engines. And make what they call a x42 engine.

Nice stuff but och expensive

Cheers Rohan

Author Topic: M42 weaknesses also apply to M44? (Read 4863 times)

johna

M42 weaknesses also apply to M44?

Darky

Re: M42 weaknesses also apply to M44?

johna

Re: M42 weaknesses also apply to M44?

Darky

Re: M42 weaknesses also apply to M44?

dsm2002

Re: M42 weaknesses also apply to M44?

Darky

Re: M42 weaknesses also apply to M44?