My M38A1

aaron92685 · May 7, 2010

modified said:
you got oil and not fuel on the plugs? I'd torque the head down to spec and do a vac check and then compression. how was your oil psi at operating temp? how's your running temp?

I can smell gas on them but they are oil soaked also. Running temp was about 190... and maybe 40 50 psi while driving. I will look again tonight. I seam to have good oil pressure so makes me think the bearings are good. I will re torque the head right now and we will see if they were off at all.

aaron92685 · May 8, 2010

So I started it up this morning and looked it over more. I did not see any bubbles in the water. Oil Psi at idle is about 12 psi when i rev it up the pressure hits about 30 psi. I TQ the head down to 65 FT LB adjusted the intake valves while I was there. The engine runs about 185 190 degrees. At idle it smokes just a little but when I rev it up It smokes really bad. Blue smoke with oil residue in the exhaust. I'm about 99.9% sure that my rings are shot or my valve guides are worn. I have no idea how many miles are on the engine. It has been sitting for about 10 years or more.

modified · May 8, 2010

ah bummer, at least your chances of a cracked block or head has deduced....

aaron92685 · May 8, 2010

Well that gives me a reason to rebuild it. I am waiting for my cylinder leak down tester to come in the mail and then i can see if it is valves, rings or it still could be a leaking head gasket that is letting oil by when returning to the block. Thanks for ideas.

aaron92685 · May 8, 2010

Here is something I have not dealt with before, I checked my dip stick and noticed my oil was level was high. So I drained some oil out. When I drained the oil it was thin and smells like gas..... Now that has me thinking. Every time I start, it it acts flooded (takes fore ever to start and smells like gas) I just thought I was pumping the throttle to many times but I only pump it 3 or 4 times. Now with all this gas in the oil could that be thinning out the oil causing it to leak past the valve guides and rings? So what could be causing the gas to get in the oil? float in the carb not working right? tell me your thoughts

clinto · May 8, 2010

aaron92685 said:
Here is something I have not dealt with before, I checked my dip stick and noticed my oil was level was high. So I drained some oil out. When I drained the oil it was thin and smells like gas..... Now that has me thinking. Every time I start, it it acts flooded (takes fore ever to start and smells like gas) I just thought I was pumping the throttle to many times but I only pump it 3 or 4 times. Now with all this gas in the oil could that be thinning out the oil causing it to leak past the valve guides and rings? So what could be causing the gas to get in the oil? float in the carb not working right? tell me your thoughts

M38A1 fuel pumps can leak fuel into the oil system. Not sure how to troubleshoot them.

NDT · May 8, 2010

Before you rebuild the engine, change the oil, and disconnect the positive crankcase ventilation valve. If the oil level is high enough for the crank to hit it, the agitation will send liquid oil into the PCV and subsequently the intake. This occured on my M38A1.

Also, if the fuel pump diaphrams are old, like more than 10 years you mentioned, you can count on them to rupture at any time. The pump is bench rebuildable.

aaron92685 · May 8, 2010

NDT said:
Before you rebuild the engine, change the oil, and disconnect the positive crankcase ventilation valve. If the oil level is high enough for the crank to hit it, the agitation will send liquid oil into the PCV and subsequently the intake. This occured on my M38A1.

Also, if the fuel pump diaphrams are old, like more than 10 years you mentioned, you can count on them to rupture at any time. The pump is bench rebuildable.

The fuel pump is a rebuilt that i just got back form kaiserwillys.com about a week ago. And I have only ran it twice with it installed. The one before it was a brand new CJ5 pump. Is there anyways to test to see if the pump could be leaking fuel into the engine? I am going to change the oil but I don't have a PCV hooked up. The crank case is just venting into the atmosphere right now.

aaron92685 · May 9, 2010

So tonight I pulled the carb off and looked down into the intake and I can see gas pooled up in the intake were gas is leaking out of the carb. I took the carb apart and cleaned it. Tomorrow I am going to change the oil and install the carb and see what happens.

aaron92685 · May 9, 2010

I changed the oil using 30W oil like the technical manual says installed the cab and drove it around. By the end it was not smoking as bad but still smoking...... I'm going to check and see if the oil has any gas in it tomorrow. And if it still acts flooded when I try to start it. Has anyone tried to pressure check a fuel pump to see if it leaks? I think I might try that. Just to make sure it is not leaking gas into the crank case.

modified · May 9, 2010

sounds like you may have a hole in the Diaphram of your fuel pump. If that is the case, check if the vendor will repair or replace. (still have receipt?).

-I'd pull the oil pan get it thoroughly cleaned and inspect everything when your down thar.
-change gasket, blah,blah,blah
-straighten your oil pan.
-reassemble and oil it back up .
-remove faulty fuel pump and repplace with known good one or,
get a 24 V electric fuel pump like the ones used for the Southwind Vehicle heaters (facet or Carter) you should be able to run either without the need for a fuel press reg.
-clean out air filter and change oil in..
-check carb float level clearance at 9/64" (not 1/4")
put back together..
-clean all plugs
-check compression dry (might as well understand the wear of your cyl /valves now)

crank her to start
the f134 requires no pumping of the throttle to prime carb (that is if all is to spec)
method is pull choke about 1/2 out of its cable travel and set throttle cable 1/8th out for holding rev idle once motor starts.
adj throttle to 1200 rpm by ear.
let rev till temp at 135-140
push throttle cable back for rpm at 600 and temp till 160-180
vacuum test....
good link How to Use and Interpret a Vacuum Gauge
observe needle behavior.
set air /fuel on YS carb. close the mix screw in and back out 1/4 turn till you reach best vac smooth idle. take screw back in slightly for leanest margin.

check timing. (have you a timing mark on your Pulley and pointer designating TDC and 5 deg AdV?

test drive.

remember... we are still trying to find out if indeed you need to pull the motor for a rebuild

aaron92685 · May 10, 2010

modified said:
sounds like you may have a hole in the Diaphram of your fuel pump. If that is the case, check if the vendor will repair or replace. (still have receipt?).

-I'd pull the oil pan get it thoroughly cleaned and inspect everything when your down thar.
-change gasket, blah,blah,blah
-straighten your oil pan.
-reassemble and oil it back up .
-remove faulty fuel pump and repplace with known good one or,
get a 24 V electric fuel pump like the ones used for the Southwind Vehicle heaters (facet or Carter) you should be able to run either without the need for a fuel press reg.
-clean out air filter and change oil in..
-check carb float level clearance at 9/64" (not 1/4")
put back together..
-clean all plugs
-check compression dry (might as well understand the wear of your cyl /valves now)

crank her to start
the f134 requires no pumping of the throttle to prime carb (that is if all is to spec)
method is pull choke about 1/2 out of its cable travel and set throttle cable 1/8th out for holding rev idle once motor starts.
adj throttle to 1200 rpm by ear.
let rev till temp at 135-140
push throttle cable back for rpm at 600 and temp till 160-180
vacuum test....
good link How to Use and Interpret a Vacuum Gauge
observe needle behavior.
set air /fuel on YS carb. close the mix screw in and back out 1/4 turn till you reach best vac smooth idle. take screw back in slightly for leanest margin.

check timing. (have you a timing mark on your Pulley and pointer designating TDC and 5 deg AdV?

test drive.

remember... we are still trying to find out if indeed you need to pull the motor for a rebuild

There is allot of good info here Thank you for you help makes it easier to trouble shoot. When I bought the Jeep I replaced the air filter element and oil. As for the carb I rebuilt it and I made a little cardboard tinplate for the float so I am about 99% sure that it is at 9/64 I double checked it when I had it part again. I do notice the junk rebuild kit I bought the gaskets are all leaking gas out the side and I Imagen it is leaking down the throat of the carb also. I am going to order a new rebuild kit from Midwestmil John has always gave me good quality stuff. I am going to do a vacuum test on the fuel pump tonight and see if I got a leak in it. For the good news. my compresson in all 4 cylinders are the same.... about 110 PSI. The TM says 100-125 PSI with no more that 10 PSI diff between cylinders. But that is about were I am at. Through out the week I am going to pull the oil pan I know there is crap in it. When I drained it I stuck my finger in the drain hole and I can feel crap in there I ran a magnet in there and came back with some metal dust witch is prob norm who knows how many miles are on it... I will keep you posted on what is going on. Again thanks for the help.

modified · May 10, 2010

well, I think we've all been there. I've forked so much cash on parts I really did not need based on impatience and ignorance and the occasional "un-warrented"- "GET-R-Done!!!" which you leaves me bleeding somewhere, sometime. A methodical and systematic approach is just so much more enjoyable and rewarding when you realize it only cost you time and patience. with money still left in your wallet. :beer:

"...110 psi" that is dry compression or wet compression? a wet compression will tell you about the rings.... regardless, thats good news.
maybe you are just running rich

john and Goerge Baxter have the best rebuild kits.
"THEN AND NOW"(Antique Auto Parts Cellar) has the best REBUILD kits for the fuel pumps.
I'd also back blow compressed air through your entire fuel line with mineral spirits or volatiles just to clear the rust mud that has a tendency to settle on the lower pitches throughout your line routing.
-check for pin holes in your line and also pick up tube that can give you false reading on your pressure test ...
-make sure your breather vent in the gas tank is free of obstruction ...
-dbl check gas tank cover that (if the fording type) that it is open and not closed for fording.

aaron92685 · May 11, 2010

modified said:
well, I think we've all been there. I've forked so much cash on parts I really did not need based on impatience and ignorance and the occasional "un-warrented"- "GET-R-Done!!!" which you leaves me bleeding somewhere, sometime. A methodical and systematic approach is just so much more enjoyable and rewarding when you realize it only cost you time and patience. with money still left in your wallet.

"...110 psi" that is dry compression or wet compression? a wet compression will tell you about the rings.... regardless, thats good news.
maybe you are just running rich
john and Goerge Baxter have the best rebuild kits.
"THEN AND NOW"(Antique Auto Parts Cellar) has the best REBUILD kits for the fuel pumps.
I'd also back blow compressed air through your entire fuel line with mineral spirits or volatiles just to clear the rust mud that has a tendency to settle on the lower pitches throughout your line routing.
-check for pin holes in your line and also pick up tube that can give you false reading on your pressure test ...
-make sure your breather vent in the gas tank is free of obstruction ...
-dbl check gas tank cover that (if the fording type) that it is open and not closed for fording.

I have new lines installed on the jeep but no fuel pick up So right now i just blocked off the hole for it and ran a rubber fuel line from the bottom of the tank to the fuel pump with a filter. I ran out of patience waiting for the fuel pick up. So I know the fuel lines are good lol. As for the compression test when you mean dry, with out putting oil in the cylinders?

modified · May 11, 2010

aaron92685 said:
....As for the compression test when you mean dry, with out putting oil in the cylinders?

yup, do a wet with oil and check your readings. hopefully it wont jump to much.

aaron92685 · May 11, 2010

So today I got a chance to work on the M38A1 for a bit. I hooked up a vacuum gauge to the full pump and it held 20 lbs of vacuum so I don't think it is leaking. I ran the engine to operating temp and hooked the vacuum gauge and the needle was jumping back and fourth between 14 and 20 looks like a sticking valve and leaking valve guides.... I adjusted the carb to about a 1/4 turn out and ran it and it still smokes. I wish it did not smoke the engine runs really good.

modified · May 11, 2010

worn rings and pistons.

If the compression reading goes up with oil in the cylinder, the piston rings and cylinders may be worn and leaking pressure. The oil will temporarily coat and seal bad compression rings to increase pressure; however, if the compression reading stays about the same, then engine valves or head gaskets may be leaking. The engine oil seals the rings, but does not seal a burned valve or a blown head gasket. In this way, a wet compression test helps diagnose low-compression problems.

Do not put too much oil into the cylinder during a wet compression test or a false reading may result. With excessive oil in the cylinder, compression readings go up even if the compression rings and cylinders are in good condition.

aaron92685 · May 11, 2010

So I did a wet compression check on the A1 and I got a good 119 PSI in all 4 cylinders. That is 9 more PSI than dry..... From what my vacuum gauge says that I have a sticking valve and worn valve guide. I like to condemn things to quick sometimes. What do you guys think? Rebuild? Anymore ideas?

modified · May 12, 2010

leak down test will isolate valve conditions and head gasket issues. ... the increase in compression when wet says, worn rings.

sorry to say that is my humble assessment.

though, you might be able to just to hone and install new rings.

but a machine shop is best suited to determine that . At that point, you'd want to check the rods, new bearing, valve guides, install hardened exhaust valve seats, deck head, new springs, valves so on...$$$$$$$$$$$$

thats the worst case scenario. aua

aaron92685 · May 12, 2010

I think I am going to start calling around to machine shops this week and start getting a price on machine work. Then I can build it in my garage as money permits. Rings, bearings, seals and gaskets, valve parts and timing chain. Price wise it should not be to bad. Big cost is going to be the machine shop. I have all the tools I need and a engine stand. But then there is the clutch, transmission and transfer case I might have a new M38A1 before I am done....

My M38A1

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