Head gasket sealer on John Deere 750

   / Head gasket sealer on John Deere 750 #41  
A new head gasket leaked on my John Deere 750. Compression gases were coming into the cooling system after about 5 hours of use.

I bought a new head gasket from the John Deere dealer. What is the advisability of using head gasket sealer before installing it? If so what product would you recommend?

The engine manuel says not to use anything.

Should I have retorqued the head after a few hours of use?

Thank you
In the 90s I worked for Deere. We would be sent into the field to test different items as well as repair. One of the items was head gaskets. Deere was having a problem with them leaking. We were sent to random locations in the field and changed head gaskets following the established sequence and torgue values with the additional degree value determined by a degree wheel, the last step was to adjust for stretch. The one thing we did differently from other reps was we painted our head gaskets with a cheap NAPA flat silver paint. Ours were the only gaskets that did not leak and there was talk from Deere they may adapt this method. Myself and three other techs had always followed this practice and have never had problems with it. Inexpensive flat silver paint, lightly applied, install while tacky following the prescribed method for your engine
 
   / Head gasket sealer on John Deere 750 #42  
In the 90s I worked for Deere. We would be sent into the field to test different items as well as repair. One of the items was head gaskets. Deere was having a problem with them leaking. We were sent to random locations in the field and changed head gaskets following the established sequence and torgue values with the additional degree value determined by a degree wheel, the last step was to adjust for stretch. The one thing we did differently from other reps was we painted our head gaskets with a cheap NAPA flat silver paint. Ours were the only gaskets that did not leak and there was talk from Deere they may adapt this method. Myself and three other techs had always followed this practice and have never had problems with it. Inexpensive flat silver paint, lightly applied, install while tacky following the prescribed method for your engine
This coincides with @rScotty mentioning about the Yanmar engines, to apply the thinnest sealant on the gasket as possible. And before each stage to torque down, let it rest some before the next sequence of bolt torquing had to be done.

Thank you for your valuable input here.
 
   / Head gasket sealer on John Deere 750 #43  
The cylinder head may need to be pressure checked. Cracks sometimes are found between the valve seats and extend into the water jacket. The cylinder head gasket may not be your problem source, a cylinder head crack maybe. Some don't open up until engine warms up also.
Simple method is to glass bead cylinder head combustion areas and then visually inspect for cracks. A handheld magnifying glass can help also.
Money costing would involve taking to an engine machine shop for pressure check and magnafluxing of cylinder head.
Could also use Non destructive Testing (old name was NDI Non destructive Inspection). The easiest to do onsite is the penetrant testing. Clean the surfaces carefully, follow the instructions and mind the time restrictions between penetrant application and the developer. Too little or too much time in between and you get false readings. Not Hard just got to follow the instructions.
 
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   / Head gasket sealer on John Deere 750 #44  
That crack could likely be brazed up and the hole retapped for one size bigger bolt. That’s not the optimal solution but it’s really the only one short of a new block. I wouldn’t waste the time and money reassembling that without addressing the crack. It’s a little late now but the head needs to be surfaced before it’s reinstalled and the block needs to be checked for warping. The head bolts are one time use they need to be replaced. Also make sure the holes are free of fluid. Running a bolt into an oil filled hole can bust the casing. You also need check if the bolt calls for dry or oiled torque. There’s a big difference.
BIG difference so is using the correct increments (Ft Lb V Inch pounds, imperial V metric)
 
   / Head gasket sealer on John Deere 750
  • Thread Starter
#45  
I tend to buy my torque to yield capscrews from Fastenal or Motion Industries versus a dealer. OEM TTY capscrews tend to have a huge markup when sourced from a dealer. Some stuff is necessary from a dealer, some isn't.

I'm familiar with that engine as the dealer I work at part time the lead tech rebuilt one and I got the dirty job of repairing the muffler which had a stress failure in the case itself. Don't price a new muffler for it, you'll faint. I HT brazed it for the customer and Tigged the stress cracked mount bracket back on. Much, much less expensive than the replacement unit.

OEM parts today are insanely expensive. Some of it is justified but most isn't.
Thank you for the input. I'm on the fastenal website and have a question. Do I get a grade 8 bolt?
 
   / Head gasket sealer on John Deere 750 #46  
Thank you for the input. I'm on the fastenal website and have a question. Do I get a grade 8 bolt?
I don't know, a grade 8 bolt for what? Did you drill a small hole on both end of the crack to prevent it from spreading? Repair parts from the dealer are stupid expensive. I needed to replace the seat on my Steiner a couple years ago, price was just shy of $500 . I went to Tractor supply and bought a similar one for less than $100. I only keep a small supply of nuts and bolts in the shop anything I need I don't have comes from Home Depot.
 
   / Head gasket sealer on John Deere 750 #47  
If you are talking grade 8 for a head bolt you need to get real head bolts. I realize you are doing this on a budget but I don’t think you can shortcut head bolts.
 

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