M38 L-head engine problem;

LoboMike · Posted: Sun Nov 20, 2005 1:56 pm Post subject: M38 L-head engine problem;

Went to pull the M38 out of the garage and noticed that it was stiff/slow turning over. Started and ran rough with a distinct "banging" noise in the engine. Sounds like a sticky/stuck valve. Let it run briefly with no correction, so back in the garage. It's due for an oil change (plenty but a bit dirty). Ran nicely when put in the garage.

Possible carbon build up? What's the best approach? Change oil and give it a try? FWIW there's no canister oil filter installed. I have one but am reluctant and slow to install it.

All help most appreciated,
Thanx Mike

Ryan_Miller · Posted: Sun Nov 20, 2005 3:44 pm Post subject:

Mike,

I am sure Wes will get on this thread and tell you more than I can, but in the mean time if I were you I would ask myself:

1. How does the bottom of the oil sump look? (lots of sludge?)
2. What is your outdoor temp and how long ago was the last start up.

Has the engine been rebuilt recently or had any other problems.

I know Felix went through this last year and you should be able to find several long threads on the M38 G503 forum.

If I understand you correctly, the sound stopped prior to parking back into the garage.

Wes knows a lot more than I and he will probably post on here soon.
_________________
Ryan Miller
MVPA # 22010

LoboMike · Posted: Sun Nov 20, 2005 4:15 pm Post subject: M38 L-head engine problem

Thanx for reply; temperature is low in high 20's at night, was high 40's to low 50's when I started it up.

It was running fine when I parked it about a week prior to this incident. I'm going to drain the oil, can't remember for sure but think it's 30/10w.

I'll check for metal in the oil, etc.

Keep the suggestions coming.

LoboMike · Posted: Wed Nov 23, 2005 7:15 am Post subject: M38 L-head engine problem;

It's a stuck valve in #4 cylinder. Bummer. Any suggestions on getting it loose, non-invasive hopefully? I added Marvel Miracle to the fuel, but hate running the engine in current state. Could I just pore some into the cylinder via the spark plug hole and let is soak?

Also, changed the oil and intended adding some Marvel to the oil, but put 4 qts in and it shows full on the dip stick. Manual calls for 5 qts and that's when I planned adding a 50/50 mix of oil & Marvel. Any thoughts?

Thanx Mike

Ryan_Miller · Posted: Thu Nov 24, 2005 7:05 am Post subject:

Mike,

That sounds like a start. You might put some in the gas too. You are limited to what you can do externally without tearing things down.

Wes should be back soon to give you a solid answer.

How long has it been since your engine was rebuilt?
_________________
Ryan Miller
MVPA # 22010

LoboMike · Posted: Thu Nov 24, 2005 7:16 am Post subject: M38 L-head engine problem

Engine was rebuilt about 3 years ago and is really in good condition. I think I created this issue just warming the jeep up in the driveway and not taliking it out for a real run. I'm thinking carbon build up is sticking the valve. It's currently soaking up Marvel MO through the spark plug holes (I did all four cylinders as a precaution). Hopefully this will loosen things so I can run it out on the rod.

In sefl defense the only reason I warmed it up in the driveway the last few times is because I put all the winter canvas on and the driver's door handle needs repair (won't hold door closed). I'm concurrently working on that also.

I'm cautiously optimistic. If this fails I'll remove the "valve plate" (correct term?) and see what I can achieve. Can I just go to NAPA etc. for a replacement gasket?

Thanx to all and Happy Thanksgiving!
Mike

Ryan_Miller · Posted: Thu Nov 24, 2005 7:31 am Post subject:

Mike,

The cylinder soaking sounds like a good idea.

I would not be afraid to pull the valve cover plate to take a look at things as it only takes loosening two bolts and a new gasket.

It sounds as though you have done the right things so far. Carbon build up sounds the most likely. I would bet more from bad luck, so don't blame yourself too much.

I usually put a little marvel mystery oil in the fuel on my antique vehicles. I have heard praise and condemnation for that so I guess that one is a personal preference.

Keep us updated on your progress.
_________________
Ryan Miller
MVPA # 22010

MajBen · Posted: Sat Nov 26, 2005 3:07 pm Post subject:

Hi Lobo, I had a very similar problem a while back. My problem was gasoline that I had let set for a period of time, not very long actually and it turned to varnish or laquery thinner (forget) and stuck 3 or 4 valves. I had to remove the valve cover and the head. Very carefully, I started forcing the valves up and down after spraying them with the solution they sell at Wal Marts to put into gas to prevent this from happending. It took a long time, but got them free enough to run the engine. I drained the gas and put in fresh with a lot of this solution. Forget the name but they had a selection of products to remove the crap.

I too would be reluctant to run the engine with one stuck as you describe. Doubt this will help but just wanted to add my experience. I sure keep some of that stuff in the tank now for each tank full. SF Ben
_________________
Semper Fi Ben M38 & M100

LoboMike · Posted: Sat Nov 26, 2005 3:37 pm Post subject: M38 L-head engine problem;

Thanx Ben. The gas in the tank has been in there for a while, months at least. I'll look into that and get some gas additive.

I'm going to give it a try tomorrow. Been soaking for about three days. Gonna put a towel over the spark plug holes and turn it over a few turns, then repeat after putting in the plugs.

Then cross my fingers and give it a go. Wish me luck folks.

Mike

Ryan_Miller · Posted: Sun Nov 27, 2005 9:14 am Post subject:

Mike,

Good luck today with your engine!
_________________
Ryan Miller
MVPA # 22010

LoboMike

Success folks! Took Ryan's advice and put a towel over the open spark plug holes and turned it over a few turns. Cleaned up the plugs a bit and re-installed them. I should Have pushed it out of the garage (make a note). It was a little stubborn starting, but when she did the smoke thickly filled the garage. To make matters worse she stalled and I had to repeat the process in the fog in the garage.

I let it idle for a minute or so speading bluish smoke thoughout the yard. Smoke was so thick it brought back memories of being down the shore (that's at the beach for non-NJians) when they use to spread DDT for mosquito control from surplus jeeps. Jeep smoked longer than I expected but finally cleared up and it's running fine now. Think I'll add a little MMO at oil changes and fuel ups.

Took the opportunity to install a battery cut-off we discussed awhile back. Now to finally install a filter Maj. Ben kindly gave me way too long ago.

Shocked

Thanx everyone for your help, Mike

MajBen · Posted: Sun Nov 27, 2005 12:06 pm Post subject:

Hi Lobo, congratulations, sure am glad for you that Ryan's suggestion did the trick. I'll bet you a good Ozark cup of coffee that the stuck valve was caused by varnish with the old gasoline.

I am glad you brought the subject up as I got to thinking about when I last started Leatherneck and I think it was at least 2 months ago so I went out and started it and ran it around the sub-division for 4 miles. First, I put in 10 oz of Sta-Bill fuel stablizer that I bought at Wal-Marts. We are a believer in that stuff and use it in all of our small engines. Before we had trouble of the VARNISH collecting over the winter. Really suggest in the strongest way that you add something to your gas even though you got it started this time and it cleared up.

Leatherneck did not start the first turn as it has been as it had set for the time but I gave it a couple of swigs from the primer pump and it was ready to go.

Take care and Semper Fi Ben
_________________
Semper Fi Ben M38 & M100

Ryan_Miller · Posted: Sun Nov 27, 2005 7:29 pm Post subject:

Ben,

Glad to hear things are running smoothly!

Mike,

I am glad you dodged that bullet! Cool

I bet Ben is correct with the varnished gas. You did the right things and have had the engine rebuilt, etc.

Seems I read or maybe just heard some where that the new fuels have additives to make them burn cleaner, but the side effect was that the fuel goes bad much ealier than usuall.

Anyway, we are very glad things worked out. Makes me sick just thinking about a new engine with a stuck valve. Razz

Mike, I usually throw a little Marvel Mystery Oil in with my gas on the antique vehicles. I am sure there are many opinions...
_________________
Ryan Miller
MVPA # 22010


Create an account	Home · · Forums · · Articles · · Downloads · · Photo Gallery


PHP-Nuke Copyright © 2005 by Francisco Burzi. This is free software, and you may redistribute it under the GPL. PHP-Nuke comes with absolutely no warranty, for details, see the license.