Blown Head Gasket - M38

[RonD2]

Thanks Wes. I'm hearing that the crack is the show stopper? Pull the motor and have it repaired. Might as well do a full re-build at the same time, needed or not. That would certainly eliminate any uncertainty about the overall condition of the motor, something I don't have now because I don't know it's true history. Other than it was running good and had no other issues up until this.

Now don't shoot the messenger, but I was thinking about troubleshooting the problem. The TM has a chapter just for replacing the head gasket (nothing else), like a blown head gasket with no other issues might've been a common enough occurrence?

Hypothetical question: ignoring the crack, if the block deck is within tolerance and valves/valve seats are good, and the motor was otherwise running good with no other issues or leaks, wouldn't I just replace the gasket and run it?

Now the search for a reliable, reputable L134 rebuild shop begins.....your pointers to some would be greatly appreciated.

[4x4M38]

Wes,
If he goes that route would it make sense to replace the valve seats with
newer style with different metallurgy?

[RonD2]

Hey Brian,
It sure would make sense, if they aren't already there. The seats look pretty fresh to me. And I don't use ethanol fuel anyway. Can you tell by looking? I can't. Not without some coaching.

My point was that I thought there was more than an even chance the gasket was installed improperly. Upside down maybe, goofy mix of improperly sealed and improperly torqued bolts and studs. But I'm the rookie looking at it. What the heck do I know? That's why I like this forum so much.

Right up until it boosted all the coolant out the radiator cap it was running fine. And compression hasn't changed since. No reason I can find to think anything else caused this.

It seems to me that the small crack in the block is now driving the solution.....to a full rebuild. Ouch. Find somebody who knows what they're doing. Double ouch. And charges a fair price. Triple ouch.

[wesk]

The TM has a chapter just for replacing the head gasket (nothing else), like a blown head gasket with no other issues might've been a common enough occurrence?

Try to look at head removal and re-installation as a stand alone task that is often required for many different reasons. Not just a blown head gasket. Why would there be so much talk for the head gasket? Well it has to be changed every time the head comes off for whatever reason. I didn't find this stand alone chapter on head gasket replacement in any of the TM's. Give us a TM # and page #1

Hypothetical question: ignoring the crack, if the block deck is within tolerance and valves/valve seats are good, and the motor was otherwise running good with no other issues or leaks, wouldn't I just replace the gasket and run it?

Ron, there you go again with that "Ignoring" word again. Any intelligent technician would not ignore the crack for any reason. Perhaps you meant to say "Hypothetical question: If there was no crack" Now that is a reasonable statement. Now if we can only get you to acknowledge that BOTH the block deck & the head must have trued surfaces. So now with no crack and the head & block deck perfectly true and the valves and seats completely serviceable, yes, you would simply replace the gasket following the GASKET MANUFACTURER'S INSTRUCTIONS not the TM or Willys manual.

Now the search for a reliable, reputable L134 rebuild shop begins.....your pointers to some would be greatly appreciated.

Picking the shop you should rely on reputation. Ask around the garages where they send their work. Get as much personal testimony from the selected shop's clientel as you can get. You may want to consider a simple set of questions for the shop foreman that will give you some insight into his working knowledge of the Willys L & F 134's. The first question is as a simple as: Do you have a copy of the Willys overhaul manual? Other questions could be:

1 - What can be done if my lifter bores are worn past limits?
(Willys supplied a single oversize for the lifters.)

2 - Is there anything special about the relationship of the distributor to the oil pump? (Yes, the oil pump must be clocked correctly to set the distributor timing correctly.)

3 - How much will a set of Cam bearings costs?
(There is only one cam bearing!)

4 - Do I really need to keep the partial flow oil filter on my L134?
(Yes, partial is better then none. )

[RonD2]

Well, at the risk of being chopped off at the knees again, here goes.

Not counting several other reasons mostly having to do with fun, I've sunk too much coinage into this hobby to ignore, take short cuts, or half-a$$ any repair. I thought that might be evident by now, or at least earn me a "benefit of the doubt" after a couple of hundred posts? I guess not. It's difficult enough just to use the right word or phrase to describe something. Not many can do it effectively, including me. I think it's mostly the nature of communicating from miles away with folks you've never met. Sometimes it's something else. People hear what they want to hear, written or spoken. I'm no exception. Getting to the nuggets should be more fun. Even the ones that lead to bad news like unscheduled engine overhauls. I'm willing to pay the dues.

The head gasket "chapter" (re-phrase "paragraph" with my apology!) is 103. CYLINDER HEAD GASKET on page 106 of TM9-8012.

Section IV. TROUBLESHOOTING, Paragraph 85 COOLING SYSTEM, subparagraph (10) INTERNAL LEAKS on page 87 refers to paragraph 103.

I believe I understand what they mean. No need to expand.

And yes, I acknowledge that both the head and block surfaces must be true and within specs. My middle name isn't Bubba, it's Richard. But you can call me Dick.

[wesk]

Somebody once asked me, What is the difference between a pilot and a mechanic?

Being both I had the perfect answer:

A pilot has to land on a 75 to 300' wide runway somewhere in the first 1,000'.

A mechanic has to determine clearances that affect life & death in 0.001" or less!

So when a non mechanic thinks I am too picky, well what can I say!

[RonD2]

Hi Wes,
Well, I'm not a pilot, and only a wannabe mechanic. But I have parachuted out of a perfectly good airplane. Does that count?

Anyway, I have another question to test your patience regarding my recent gasket failure experience that I hope you can help me understand?

When I pulled my head, there were no lock washers under either the bolts or stud nuts. I didn't think much of it at the time, but pondering the manuals like you've taught me (did you smell something burning?) has somewhat confused my grape.

TM9-8012 doesn't mention lock washers that I can find, but the engine manual TM9-1804A, paragraph 36. REMOVAL OF CYLINDER HEAD, on page 44, says "Remove the lock washers and nuts that secure the cylinder head to the cylinder block....". Then in the ORD9 SNL G-740 on pages 26 and 27 (Cylinder Block and Head) I see nuts and studs --- but no lock washers.

I'm guessing that every mechanic learned simple stuff like this a long time ago, but I have to ask: which is it --- lock washers or not?

Thanks for the reply Professor. I sincerely appreciate your patience with my questions. It means a lot. You and this forum are the reason I took the dive into the deep end of this pool (buying 1st ever jeep at my age). Couldn't do it without you and the other gold nuggets in this forum.

[wesk]

the engine manual TM9-1804A, paragraph 36. REMOVAL OF CYLINDER HEAD, on page 44, says "Remove the lock washers and nuts that secure the cylinder head to the cylinder block....". Then in the ORD9 SNL G-740 on pages 26 and 27 (Cylinder Block and Head) I see nuts and studs --- but no lock washers.

Good point to bring up.

1 - Seldom on any make engine do you see any lock washers used under head bolts or head stud nuts. I believe that is because they interfere with arriving at the correct final torque. Even on aircraft piston engines there are no lock washers used with the cylinder hold down nuts.

2- That Par 36 is the only reference to lockwashers in any of the MA, MB or M38 manuals. Par 90 (head isntallation) makes no mention of washers.There are no lockwashers listed in the any of those same ORD 9's.

3-However if you look closely at the M38 ORD 9 SNL G740 dated 1955, there are 4 figures of the engine with it's head. Figures 01-1, 01-2, & 01-3 show no washers under any of the head nuts but figure 01-4 shows a lock washer under all three of the visible front head nuts! These do not appear in the MA, MB, GPW or GPA IPL's. Nor do they appear in the Nov 1951 M38 ORD 9 SNL G-740 figures 01-1, 01-2, 01-3, & 01-4, however the three forward most nuts shown in figure 01-5 show 3 washers. However they can both be explained by remembering that oil filter support bracket and the left front oil hose support bracket were held down by these three nuts and they might have left the presence of these steel brackets under the nuts in those figures.

The Short Answer! NO WASHERS!

[RonD2]

Was this unmarked gasket installed upside down? This is the side against the block as it was disassembled:



This is the other side against the head as it was disassembled:



This is a new FelPro 7285B gasket showing the side marked "This Side Up" and "Made in USA":

[/img]

This is the other side of the 7285B that goes against the block:



This is another crack on the #3 exhaust valve:




Pulling the motor for a visit to the machine shop.....

[wesk]

Was this unmarked gasket installed upside down?

Only way to be sure weather it was installed right side up or upside down is to confirm it's manufacturer and verify from their directions. I would not waste time comparing the old unknown source gasket to your new known source gasket. In the majority of cases the side of the gasket that faces the head is the side with "this side up" on it or with the manufacturer's trademark on it. Also most composite gaskets which have differing amounts of metal on each side the side with the most metal usually faces the block.

Important thing is to make sure you follow the gasket manufacturer's instructions when you install their gasket.

[RonD2]

Thanks Wes. I never figured to waste time trying to figure out the cause of a failure, even if it was the guy before me that did it. I guess I won't dwell too long on this one because of the other issues involved, but...

...when I read the manufacturer catalog installation tips for the new gasket that say a gasket "should be" coated with a sealant --- but don't specify by part number (out of the thousands they make) the gasket they say to use it on. Is "should be" a command, or a suggestion? Why not remove all doubt and say "must be"? Maybe it's just numb-nuts like me wasting time asking stoopid questions about things that mechanics already know.

For instance, the Fel-Pro Master Catalog, on page 1279, Installation Tips:

https://fme-cat.com/digipubZ/Fel-Pro-Ma ... ge%22:1304}

says a sealant should be used on a gasket like the 7285B. Really? Which side? Both sides? I guess I'll call their hot line and ask. I smell more wasted time headed my way getting by their automated computer answering machine before I get to somebody who can answer the question....I hope the wait time isn't too long.

[RonD2]

I'm pretty much convinced the failed gasket is a cheap unmarked POS that should've had sealant on it, and Bubba put it on upside down with a monkey wrench.

Instead, I'm going to learn how to tear down and build up a Go-Devil!

[wesk]

If you have a brand Felpro in the box then it comes with instructions on the box and sometimes on a single sheet of paper in the box.

My gut tells me you are trying to overthink all of this. It's a good time to relax the brain muscles and slow down and smell the roses.

A little web trotting offers a wee bit of help.

https://www.fme-cat.com/Docs/1425.pdf This Felpro very General gasket history and prep.

https://www.felpro.com/technical/tecblo ... skets.html This is a Felpro "Which Side Up" bulletin.

[RonD2]

Thanks Wes.

I do have a tendency to overthink stuff I know little or nothing about. Feeble attempt to take nothing for granted. Been bit in the a$$ some times thinking I "know" something when I really don't. Good thing is from what I can tell, the M38 is pretty forgiving of ignorance, even well placed.

My new Fel-Pro 7285B came in a sealed package with zero instructions. Just a label.

Good stuff, especially the Cylinder Head Gasket Installation, Federal-Mogul Document #1425. Read it twice. Printing it for my binder. Pretty cool that they use a (kind of mangled) L134 head for their torque diagram! Lame avoidance of copyright infringement I bet. It answers and confirms some questions, but raises others, like:

What "type" gasket is the 7285B? The kind that doesn't have to be re-torqued? Or re-torque it following the Willys manuals and conventional wisdom and cause it to fail?

I'll see what the hot-line tells me.......

Regards!

[RonD2]

The only post I could find searching "7285B" is an interesting and informative exchange over at the Fel-Pro "Break Room" tech support forum:

https://www.felpro-only.com/break_room_ ... B#pid29158