404 Deere Headgasket February 27, 2019 03:15PM
Blew the headgasket in my 4630 today. Was just bringing it to the shop to give it a once over. Had to drive it a couple miles so it was up to temp and I had to idle back on a slight hill to pass a car. When I throttled back up, it let loose. It literally blew the fire ring on #1 cylinder out the front between the head head and block. No warning signs, was running like a top last fall and is still right on the money coolant wise.


Tractor has been turned up to about 180 at some point in it's life. Supposedly has 11,000 hours (I suspect less, if anything) and has never been touched. I suspect the head must be warped pretty bad for it to completely blow the gasket out in an instant under minimal load. Either that, or could a liner be cavitated and it suddenly failed and let a shot of water in? Is cavitation a known problem on these engines?



Anyway, a few questions for those of you who know these 404's (1977 model):


Should I get new head bolts? I have read that they were upgraded at some point, but I couldn't tell if '77 would be upgraded already or not.


I am planning on having the head planed and will touch up the valves myself. What should I shoot for on valve protrusion? Top of spec or can I go a little more for more compression (better starting)?


Any other suggestions while I have the head off? (Will probably roll bearings while it's in the shop, not that they have anything to do with the head).
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Re: 404 Deere Headgasket March 02, 2019 01:33AM
With the engine having 11,000 hrs there are a lot of things that should be addressed . (1) yes you need new head bolts head bolts are cheap and one time use is a good practice. (2) you will need to plain it , yes it is warped .(3) you will also need new valve springs , they get weak and shimming them is a get by they will break and drop the valve. With that many hrs it would be a good idea to replace the valves and at very minimum the exhaust due to heat. Do not get fancy with the valve protrusion set at the high side of spec and you will be fine , it would be a wise idea to get your injectors cleaned and checked for better starting.
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Re: 404 Deere Headgasket March 03, 2019 04:59PM
If you pull the pan check the Cam for wear at the oil pump drive gear.. Or pull the tach drive and check the oil pump drive gears. Normally with that many hrs the gears are getting pretty worn.
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