B7100 head gasket leak added info

[sevengutters]

Looks like not so good news on my leak . After tearing everything down and cleaning up the clutch , pressure plate , flywheel and adaptor plate .
I seen where antifreeze was weeping from the gasket area and thinking it WAS the gasket . Well took off the cylinder head cleaned it up and found a crack in the casting .
There was some oil on top of the middle piston The other two just some carbon buildup. The middle piston has some rough edges on the top circumference of it .
So I need some input on how much would be sufficient .The tractor is in good condition and I feel worth while putting some money into it .

 

[Jim L.]

Options on the crack would be: new cylinder head; trade this cylinder head for remanufactured head; tig weld the crack; cold stitch the crack. Last two options assume no other problems but the large crack. Probably should have head examined for other problems.

If you will post some good pictures of the piston someone may be able to diagnose. I would be looking for coolant seeping in due to the rough edges. And of course, where did the oil get in? Gasket?

 

[sevengutters]

Looks like not so good news on my leak . After tearing everything down and cleaning up the clutch , pressure plate , flywheel and adaptor plate .
I seen where antifreeze was weeping from the gasket area and thinking it WAS the gasket . Well took off the cylinder head cleaned it up and found a crack in the casting .
There was some oil on top of the middle piston The other two just some carbon buildup. The middle piston has some rough edges on the top circumference of it .
So I need some input on how much would be sufficient .The tractor is in good condition and I feel worth while putting some money into it .

I posted some pics of the piston tops after I wiped the oil off the front and center one . You can also see the oily valve areas in the pic with the crack head .
I ordered a recon head with valves and seats . Not sure if the pistons and rings shouldn't also ... Thanks for the professional knowledge .

John

 

[sevengutters]

I posted some pics of the piston tops after I wiped the oil off the front and center one . You can also see the oily valve areas in the pic with the crack head .
I ordered a recon head with valves and seats . Not sure if the pistons and rings shouldn't also ... Thanks for the professional knowledge .

John

More pics ....

 

[North Idaho Wolfman]

If you could post pictures of the each set of valves on the head.
curious because one of the pistons looks like it's being washed, could be a coolant leak or it could be a bad injector.

Take it to a head shop and have the head pressure tested to make sure that is the only place it's cracked and leaking.

Then if the only leak is the crack in the back.
They may be able to fix it by welding or you could fix it as below.
Clean it very very well with brake parts cleaner and a stiff wire brush.
Set the head so that the crack is strait up in the air.
Use a 2 part epoxy for metal and coat the crack with a small amount and work it into the crack the re-coat with more material to make a good seal.

You could have it pressure tested again or just give it a try.

Note: I'm not 100% convinced that the head is cracked in the back it looks like it could just be a casting abnormality.

 

[sevengutters]

Here are some pics of the valves . I forgot to mention that when pulled the head off there was some coolant around the middle piston when tuned up and down . The top of the head is pretty oily .
I did just order a new reman head on ebay with valves and seats and head gasket. If the other one is not cracked I'll offer it for sale later after I have it tested . Pistons and rings ???? Thanks

 

[sevengutters]

More valve pics ...

 

[torch]

I can see what *might* be a crack on the ground face at the rear in the general vicinity of the cooling passage, but it doesn't seem to be anywhere near a cylinder. You've already ordered a new one, but if it was me, I would have assembled over a new head gasket and if it was indeed weeping out of the casting, then used CRC "Blockseal". Great stuff if you follow the directions religiously.

 

[sevengutters]

Thoughts on pistons and rings etc. since I will be putting a new head on it .

 

[torch]

Thoughts on pistons and rings etc. since I will be putting a new head on it .

I think the best guidance would be to have done a compression test before disassembly, but since it's too late for that now, the best you can do is measure the bores at multiple points checking for taper and out-of-round. That won't directly tell you how the pistons and rings are but are a good indication of engine wear. IE: if the bores are well-worn, then the pistons and rings probably are too.

How many hours on the engine? Blowing smoke? Making funny noises (well, more so than any other diesel)?

 

[sevengutters]

It has 1100 hours on a working meter . Had some blowby , smoke some probably more than some. Its my first kubota so not sure . No strange noises to talk about.It has a newer radiator dated 2004 . Its really a clean machine without much physical neglect .
Engine neglect not known (1991) HstD

 

[North Idaho Wolfman]

I can see what I think is a crack in Photo #2 so yea new head is in order.

As far as the bottom end goes a compression test would have been good, but I think your numbers would have been skewed by the cracked head.

If you want to get into the bottom end pull the pistons and mic them and bore gauge the cylinders, greatest wear will be at the top, about 1/2 down.

If it needs sleeves and pistons, you should seriously consider finding a good running D950 to replace it, as the cost will be less for a good motor than to rebuild that one.

 

[sevengutters]

I can see what I think is a crack in Photo #2 so yea new head is in order.

As far as the bottom end goes a compression test would have been good, but I think your numbers would have been skewed by the cracked head.

If you want to get into the bottom end pull the pistons and mic them and bore gauge the cylinders, greatest wear will be at the top, about 1/2 down.

If it needs sleeves and pistons, you should seriously consider finding a good running D950 to replace it, as the cost will be less for a good motor than to rebuild that one.

I did read here in the forum that a 950 would interchange . Would I have a lot of other costs involved other than transferring some parts over from the 750 to the 950 ?? Thanks

 

[torch]

1100 hours isn't excessive, and from the little I can see in the photos, the cylinder walls don't look scored or anything. On the downside, excessive blow-by is a potential sign of ring wear. Looking back at your first post in January, you mention it had 900 hours, so it sounds like you've put a couple of hundred on it. Did it use much oil during that time? Some oil use is normal, excessive oil use suggests worn engine components.

If it was me, given that you already bought a new head and gaskets, and assuming oil consumption hasn't been an issue, I'd get a bore gauge and/or someone who knows how to use it, and take some careful measurements. If the cylinders are still reasonably in spec (less than .006" wear max.) then I'd slap it all back together and see how it runs.

 

[Jim L.]

Asking this so that I might learn more.

Picture showing top of piston and erosion at edge. Could be coolant that caused brittleness?

On a machine with 1100 hours, would this erosion be considered inconsequential? What's typical for threshold of replacement for that type of wear on a piston?

Comments and being schooled gratefully accepted.

 

[sevengutters]

1100 hours isn't excessive, and from the little I can see in the photos, the cylinder walls don't look scored or anything. On the downside, excessive blow-by is a potential sign of ring wear. Looking back at your first post in January, you mention it had 900 hours, so it sounds like you've put a couple of hundred on it. Did it use much oil during that time? Some oil use is normal, excessive oil use suggests worn engine components.

If it was me, given that you already bought a new head and gaskets, and assuming oil consumption hasn't been an issue, I'd get a bore gauge and/or someone who knows how to use it, and take some careful measurements. If the cylinders are still reasonably in spec (less than .006" wear max.) then I'd slap it all back together and see how it runs.

Apologize . My Other mower has 900 hrs . The b7100 has just less than 1100 hrs.
I didn't even get to use it yet . Got it home in January didn't see any leaks at all. It has a nice 60" belly mower , DuAl 45 front end loader .
Oil looked dirty so I changed it . The coolant looked good and clean , inside of radiator looked clean . Right after the oil change is when I seen the dripping of coolant at the bottom of the clutch housing gasket . Was busy at work since then and now just retired getting the time to see the current week findings .
I was told it didn't burn oil , but you know how that one goes around .

 

[torch]

I assume it was reasonably close to the full mark on the stick? If the PO was trying to scam you on the oil, he probably would have changed it before putting it up for sale. But yeah, who knows; maybe he just topped it up every week in lieu of changing it.

 

[North Idaho Wolfman]

Asking this so that I might learn more.

Picture showing top of piston and erosion at edge. Could be coolant that caused brittleness?

On a machine with 1100 hours, would this erosion be considered inconsequential? What's typical for threshold of replacement for that type of wear on a piston?

Comments and being schooled gratefully accepted.

Yes coolant leaks can cause issues, but I also think he had said in another thread that previous owner used ether to start it (apologies if I'm incorrect, I follow a lot of threads), it's really not typical for there to be that much wear at only 1100 hours.
Normally you wouldn't need to worry about piston changes until somewhere in the 3000+ mark on these style of engines.
A compression test or a feeler gauge test would work in determining if you really need to change pistons.
But with as many issues as this motor has I worry about the positive gains that you might get out of putting any parts into it.

 

[Jim L.]

Thanks Wolfman. We all appreciate your generous sharing of knowledge.

 

[sevengutters]

Thanks to everybody for their advice , expertise and knowledge . I have came to a conclusion .
New Head
New Gasket
Seal (o ring )

Put it back together and see how it performs . At least the coolant issue should be resolved . I won't put that many hours on it to be concerned about pistons and rings at this point . Unless the compression is terrible . Of course More advice may be needed before assembly is done .
Thanks to Wolfman and everybody with input
I will get some pics when its completed and post them . Tractor , MMM and DuAl Loader