Posted: Wed Jun 21, 2006 2:35 pm Post subject: Oil emullsion, crack??
OK guys lets see what you all think.
A-while ago I mentioned that my m38 was losing water in a non obvious way.
This led to it overheating and surprising me.
Now I'm supposed to be going to our MVT national show at Kemble so I started checking over the jeep for the 650mile round trip, as last weekend we covered 500miles over the weekend.
Pulled the dipstick and found grey emulsion in the sump.
Now, I think the over heating may have opened up an old repair or crack in the inside of the block. The last time this engine was rebuilt was 1955!!
Tonight I drained the mush, ran flushing oil through, refilled with cheap oil. Tomorrow I'll fire her up, get her hot, take her for short run and check the oil again.
So my question is, apart from a crack inside the block, is there any place else that water could get into the oil?? Its a while since I changed a head gasket but I doubt thats where the oil and water are mixing.
The only other thing I can think of is the fording valve was accidently left in the fording postion for about 500 miles so no air was being drawn out of the valve gallery, could that have left enough moisture in the engine to cause an emulsion??
Any comments graetfully recieved,
Thanks Dave.
PS. Wes, I still have not pulled the m201 out of the garage to photograph the harness as the m38 has suddenly distracted me. Will try and get it done this weekend.
Hi Ryan,
I'm changing the head gasket today, picked one up yesterday. I've done this before but before I start.
Now,
Q1. The head gasket has metal alloy inserts that trace around the edge of the cylinder. These are pressed into the gasket but are slightly wider on one side than the other. Is this a face up -- face down thing??
Q2. I've never coated the threads before with anything, now I'm been advised to. have I just been lucky so far or should I be coating the threads with something.
Thanks,
Dave.
Right,
now the head is off.
I should really start another post because this is now moving in a very different direction.
I originally removed head the because the engine, once in a blue moon boiled over for no reason, anyway here's where I'm at now.
1. I did a compression test and found from front to back the following in PSI. 114, 113, 101, 95. This was done with a hot engine and the throttle fully open
2. Removing the head i found the inside of the engine to be absolutly bloody gorgeous. The pistons were 'as new' with concentric rings macined in the top. From front to back each piston was numbered 1, 2, 3, and 4.
3. The valves were numbered from front to back 1,1 then 2,2 then 3,3 then 4,4.
4. Cylinders 3 and 4 appeared to have been running slightly 'lean' and hot with No3 appearing the most burnt, but that's a relative term. Remember compression fell off at 3 and 4 more so at 4. BUT 3 appeared to have been running the leanest.
5. The cylinders were not scored.
6. There was no obvious connection between water galleries and head studs.
7. I did notice that there are four oblong water slits on one side of the block that match slits in the head BUT on the other side of the block the slits were in the head but blanked off in the block. I've seen this before on M201 442 engines so I assume its normal
8. Each piston had stamped on its surface its piston number then -30 and an arrow pionting toward the bore which I assume means -30 thou.
9 Why the back two cylinders are running lean I don't know but my next stop is to check and replace the intake manifold gasket.
10. The valve seats appear bright and shiny with no burning/cindering/wear.
So I don't think the water has been leaking via the cylinder head and I can't see why the compression falls off toward the rear of the engine, unless I have those valves very badly set up. Any ideas as to why the rear cylinders are running lean?
Any comments at all are very greatfully recieved.
Thanks,
Dave.
I have forgotten which way the head gasket goes. Wes should be along soon to post on this. I'll try to look it up in the mean time.
Head studs: it is a good idea to coat the threads that go into the block and communicate with the water galley. Wes recomends permatex # 1
I am not a trained mechanic, but compression is usually a function of the piston rings, cylinder walls, and the valves seating properly. What looks good may not be good.
The lean mixture could be an intake gasket problem, how is your carberator?
I hope this helps some. Again Wes is the master mechanic and should be posting soon. _________________ Ryan Miller
MVPA # 22010
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