Head gasket replacement tips and tricks.

Blueduce

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I will be replacing the front head gasket on my M35a2c multifuel this weekend. Don't worry, I'm not asking how to. I've read the TM for this particular undertaking and it seems rather straight forward. I already have the gaskets I need including valve cover, both head and exhaust manifold gaskets.
The reason for this thread is to reach out to you gear heads to see if anyone has any tips or tricks that would make this repair easier, quicker or go smoother.
I was also wondering if there is anything else I can do while I have the head off as far as preventive maintenance to the head or other engine components that would be accessible due to this project.

Thanks.
 
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Seth_O

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I did this one about a year ago; it was surprisingly easy. I used a cherry picker to get the heads off, but not sure that was necessary. Check your freeze plugs on the heads while you have them off. I took the time to clean all the turbo components and paint them with high-temp paint and replace all the fuel lines. Its also a good time to replace all the soft hoses. I examined the injectors and cleaned them as well. I bought an industrial-sized can of anti-sieze and used it liberally while reassembling. Also, make sure you have a good charge on your batteries for the first start up - I had to crank for a while to get fuel to all the injectors after the rebuild.
 

Blueduce

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Seth_0,
Thanks for the suggestions. I would have never thought of the freeze plugs inspection. I do plan on replacing all soft hoses. What did you use to clean your turbo components and injectors if you don't mind me asking. Is it just a gas soak and a stiff brush or is there a better solvent you would suggest.
I was also wondering if I should go ahead and replace both head gaskets while I already have things apart. The front one is the only one that leaks just now but I'm not sure if I should replace both or not.
 

clinto

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Check pistons for cracks while it's apart.

Now will be the time to drill and tap the exhaust manifold for a pyrometer.

Replace all freeze plugs.

Replace hoses and thermostat if they aren't brand new.
 

Seth_O

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Replace ALL the gaskets while you're in there. Its also a good idea since you're all the way in there to go ahead and pull the radiator (makes removing the bottom hose infinitely easier) and check/replace the belts.

I just wire-wheeled the outside of the turbo and cleaned it with acetone to prep for paint. The injectors I cleaned by soaking in Carb cleaner and scrubbing with a green Scotch pad. I also replaced some of the nuts and bolts that looked worse for the wear. It starts to sound like a lot, but you're rarely that deep into the engine so this is a good opportunity to do it. Most of the work can be done while the heads are at the machine shop.
 

m-35tom

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don't forget to have the heads resurfaced. no matter what anyone thinks, they will need it. it may only take .002" but it will make a big differance in how long this lasts. you are using the latest one piece gaskets?? replace ALL freeze plugs, on top of the head, both ends of the head and on the block. put stainless plugs in the heads if you can. yours may look ok when you remove them or you may see that they are badly rusted, but don't take a chance.
 

steelandcanvas

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The only other thing I can think of that hasn't been covered, is be sure and chase all your female threads with a tap and lubricant. This will insure you get the most accurate reading when torquing down the headbolts. Also, a nice thin coat of oil on you fastener will help for more accurate readings.
 

Blueduce

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Manny thanks to all who have or will contribute to this thread. It is all valuable information. One of my main issues will be funds available for this project. As most of you may know I'm retired military and disabled. I have a set of the older gaskets given to me by a friend. However, In reading the numerous threads on the common repair. Most are swearing by the newer gasket with the pressed in fire rings.
With a repair of the importance I do not want to cut any corners or use an inferior product. In saying this is there anyone out there that may have these new head gaskets or any other parts I may need for this repair that would be willing to sell to me for a small discount. I'm not looking for charity or handouts just a small break in the price.
Thanks.
 
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swbradley1

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Do both heads and everything already said and not to disagree with Jonathan but use a thread chaser instead of a tap to clean the threads out. A tap will remove material. This was covered last month in another thread.

;-)
 

m-35tom

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Do both heads and everything already said and not to disagree with Jonathan but use a thread chaser instead of a tap to clean the threads out. A tap will remove material. This was covered last month in another thread.

;-)
this depends on the tap of course. there are several taps available for each size. i always use a tap and a die but also the correct size.
 

m-35tom

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Manny thanks to all who have or will contribute to this thread. It is all valuable information. One of my main issues will be funds available for this project. As most of you may know I'm retired military and disabled. I have a set of the older gaskets given to me by a friend. However, In reading the numerous threads on the common repair. Most are swearing by the newer gasket with the pressed in fire rings.
With a repair of the importance I do not want to cut any corners or use an inferior product. In saying this is there anyone out there that may have these new head gaskets or any other parts I may need for this repair that would be willing to sell to me for a small discount. I'm not looking for charity or handouts just a small break in the price.
Thanks.
using the older style gaskets would just be, well, foolish at the least. many people sell them, i have them for $80 which includes s&h see the classified section
 

steelandcanvas

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Do both heads and everything already said and not to disagree with Jonathan but use a thread chaser instead of a tap to clean the threads out. A tap will remove material. This was covered last month in another thread.

;-)
Good catch Steve. I did mean a thread chaser and not a tap, my bad. I realize like Tom said, there are different types/sizes of taps, but just to keep it simple here the chaser is the tool for the job.
 
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andyindy

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I replaced both head gaskets about a year and a half ago, had the heads planed and used the new style head gaskets. Now one has blown again, I was wondering if new studs for the heads might help, and where to get them? I realise the next step is to have the block decked or find another engine if the deck is bad. Any thoughts? THANKS, Andy...
 

F18hornetM

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One thought, be careful cleaning fuel injectors with a brush. Soft brush maybe, but you can damage an injector tip/nozzle and your really not cleaning out the inside, only the carbon off the outside. It doesnt cost that much to have a Fuel shop clean them. I would ether do nothing to them or have them run through a fuel injector shop.
Just an idea, good luck with the repair.
 

Blueduce

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Just called Memphis. They do have the full upper replacement gasket set (in stock) which includes the new head gaskets. Not sure, can I list there price on the thread with out getting yelled at?
 

Blueduce

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A few days ago I degrease the inside of the hood and the entire engine. Then I poured some "head gasket stop leak" into my radiator. It has seemed to work for now. I'm hoping it will work till I can get enough saved up to do the job right. I drove it I drove it over 200 miles on Saturday and all seemed well. No leeks found and no more fluid blow by on the inside of my hood.
 

Blueduce

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sorry it took some time to post the picks and get the job done but here it is.

The first four picks are of the break down. It was a one man job and quite simple by following the TM page for page. I have read several threads that debate taking off or leaving the turbo on. I elected to take it off and I'm sure I made the right choice. It was a lot easier to remove and reassemble everything. I also took everyone advice from this thread an replaced all my soft hoses while she was torn apart.

The second piece of advice I took was to replace all the freeze plugs in each head. 16 total plugs. I found them at a combonation of O'rieilly's and Napa. A $15 investment well worth the time.

My only issue was I assumend that I had blown one of the head gaskets due to the engine's performance. When I finally got to them they where fine and in good shape????? I also took the advice to take the heads to be resurfaced at a local machine shop.
Good job I did. There they found the problem. I had a crack in my rear head between the intake and exhaust valves on the very back cylinder. Fortunately it was repairable and $220 later I had like new heads.

I cleaned up everything I could get to and decided not to re-hone the cylinder sleeves or replace the head bolts due to there overall good condition. When replacing the heads I had to use the older gaskets due to financial restraints. But I did take some more advice and coated them first with "Permatex" Copper Spray-A-Gasket.It worked like a champ.

The final bit of advice I took was to reset the valve lash on all the valves. A great idea since some of them where out quite a bit. I also cleaned and painted my exhaust manifold with some high temp paint before installation. The turbo also got cleaned, painted and inspected.

As far as the offset wrench everyone is talking about to remove and re-torque the heads. It is a MUST HAVE. Instead of buying one of the NOS wrenches I simply cannibalized a wrench and socket extension I bought at my local pawn shop. I took both to a buddy and he welded it up for me. Worked great...

Since I live in TX I also removed my preheater and it's fuel lines. With all the construction going on in and around the engine I also flushed the radiator and block several times before I added coolant. I also went ahead and changed my oil and all oil / fuel filters.

Make sure your battery's are fully charged before the first start. (you'll need them). Other than that she fired right up and purred like a kitten. The next day I took a 670 mile round trip from Dallas to San Antonio to pick up and tow back a deuce a budy just bought. She ran like a champ... Wish I would have done this project a year or so ago...
 

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sandcobra164

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Looking at the pictures, you're truck was doing what many of these trucks did in service. As long as it was just "wetting the block" and not dripping, the Army sent out a directive to do nothing. I even read it in a copy of PS which is the Army's monthly maintenance "update" if you will. I read them every month and my boy's love the drawings of the trucks, tanks and guns with faces. Anyhow, my truck has been doing this for the last 3,000 miles or so. I'm not too worried about it at this point with my truck. You did some fantastic work on your truck and the pictures show you replaced alot of stuff. Motivation for me when mine worsens.
 
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