Kubota head gasket issue

[Mean Jean]

Kubota L1801. North American equivalent is an L185.*

I've replaced the head gasket on it 3 times in the same number of years with the last time being a week ago.*
A leak keeps developing at the exact same spot, front left corner.*
This last time I head the machined and was told they removed*3 thousandths of an inch.*
I torqued the head bolts twice. Once after original replacement and once after running it for 15 minutes. I also followed the proper torquing pattern.*
I rinsed the rad and cleaned the fins. Didn't run it real hard so I'm doubtful it's an over heating issue.*
I have been mindful to put the head bolts back in their original homes each time. I mention this bc I'm thinking the front left head bolt may be stretched.*

What else might be causing this problem? *

Thanks you all for your help.*

I can't confirm the head gasket has failed this time. I can confirm the leak is in the same place though.

 

[crazyal]

Have you thought about pulling the block and having it decked? Chances are that's your problem. If you don't have the equipment to measure the block after pulling the head you most likely can go to your machine shop and they can measure it for you.

 

[Mean Jean]

I'm not 100% certain of the process of checking the block to see if it's "true".
Could you enlighten me?

I would like like **** to find out the block is warped.
I haven't got the time or know how to swap the block if needed.

I ran it with the rad cap removed and coolant did NOT come pouring out so the gasket has not failed yet.

Please please please let it be a stretched head bolt!

 

[KYErik]

To check the deck of the block for flatness- you would remove the head and lay a machinist's straight edge across the length of block in all possible orientations (long ways and short ways) and then make sure a really thin feeler gauge cannot be slipped under it at any point. I think the service limit for many car engines is 0.002-0.003 inches, I'm not sure about tractor engines.

 

[Don87]

I'm taking for granted that you ordered new head bolts.

 

[Mean Jean]

I haven't ordered anything yet, still putting together a game plan.
I will be ordering head bolts though.

 

[tom4018]

Check the block surface if it is ok, clean the bolt hole threads and use new bolts. Dirty threads can prevent accurate torque readings.

 

[crazyal]

It's possible that when the block was machined it was right at the limit of being acceptable (or maybe just a tad out of spec) and the person doing it was ready to go hit the saki after work and said "good enough". What you don't know is how many times before you bought it that the head gasket was replaced. While it's more work a machine shop can deck the block and if needed get a slightly thicker head gasket. It would give you basically a brand new engine after the rebuild.

 

[94BULLITT]

I would check the block like everyone has mentioned.

Use new head bolts when you put it together. You could upgrade to studs.

Have everthing hospital clean for reassembly.

Run a use a tap to clean the bolt threads on the block.

Use just the gasket, don't put anything on it.

 

[art]

What you don't know is how many times before you bought it that the head gasket was replaced. While it's more work a machine shop can deck the block and if needed get a slightly thicker head gasket. It would give you basically a brand new engine after the rebuild.

Do not use other then a factory head gasket!!! Thicker head gasket means less compression!!! Diesels need compression to run at all!!!!

 

[Mean Jean]

All great tips, thank you.

I will clean the bolt holes and replaced all the studs.
I had cleaned the original studs but a few had some grit on them.

I will torque everything and report back.

 

[Mean Jean]

I just spoke with a local guy regarding my issue.
He informs me that the top of the block has a dowel pin which actually acts as an oil gallery.
This requires an o-ring to work properly.
I don't recall seeing an o-ring, may have come off with the head gasket when I replaced it 3 years ago.

I ordered 8 new head bolts.
$10.56 a piece....ouch!

 

[Coyote machine]

As stated 'chase' the head bolt hole threads with a clean tap and blow out any debris before reassembly. Lightly oil the new head bolts and wipe off any excess oil before using. Torque to factory specs and pattern, and make sure any o-rings, etc, are properly installed.
If all the above and what others have suggested fails you might be able to get a skilled machine shop to put a slight swirl pattern on the block's surface to allow for less potential movement of the gasket between the surfaces, IF the block shows any defects in it's presentation. This is just a suggestion, NOT a proven methodology.

 

[Gator6x4]

I have seen and done a ten pound increase on torque when dealing with a chronic head gasket problem.

 

[Mean Jean]

New head bolts arrive on Wednesday.
Will clean each bolt hole and reinstall the head gasket.
I'm getting pretty good at this job.

Should I Install a new head gasket?
I'm concerned that the old one (only a week old and maybe 8 hours run time) is compressed and won't make a proper seal.

Thanks all for the great advice.

 

[94BULLITT]

New head bolts arrive on Wednesday.
Will clean each bolt hole and reinstall the head gasket.
I'm getting pretty good at this job.

Should I Install a new head gasket?
I'm concerned that the old one (only a week old and maybe 8 hours run time) is compressed and won't make a proper seal.

Thanks all for the great advice.

Yes use a new gasket.

 

[crazyal]

Do not use other then a factory head gasket!!! Thicker head gasket means less compression!!! Diesels need compression to run at all!!!!

If you deck the block your piston to head clearance could become too thin. The only cure I know of is to either shorten the rods or go with a thicker gasket.

 

[94BULLITT]

If you deck the block your piston to head clearance could become too thin. The only cure I know of is to either shorten the rods or go with a thicker gasket.

You could change the pistons or have them fly cut.

 

[crazyal]

New head bolts arrive on Wednesday.
Will clean each bolt hole and reinstall the head gasket.
I'm getting pretty good at this job.

Should I Install a new head gasket?
I'm concerned that the old one (only a week old and maybe 8 hours run time) is compressed and won't make a proper seal.

Thanks all for the great advice.

I would go with a new gasket and make sure to follow the correct torquing pattern. I've never read the Kubota shop manuals so I don't how they say to do it but some of the equipment I work on requires things to be torques to two stages (not saying that's the correct way for this application). I also like to put a little oil on things to reduce the friction (threads and washers).

 

[Mean Jean]

Attached is a picture of the dowel pin which requires an o-ring.
This acts as an oil gallery.
This is also the general area of where my leak is developing.
So.....head bolts arrive today, head gasket arrives next week.
Hopefully this is a job I won't have to do againg for a LONG time.

Thanks all for the great advise.

Mean Jean