B7100 Head? / gasket- using H20-new user

[rfoxinc]

Hello All=
I own a 1982/83 B7100 HST, [20yrs] Nice machine-

My problem is that it Has been using much coolant lately [@1/2g/hr]

No white smoke, oil is ok, but it did overheat last year...and seems to take more preheating to fire and power seems lower than before .also no steam or noise from overflow whistle anymore. rad & cap previously replaced, and there is discoloration around filler neck.

My ?'s Any further diagnosis to confirm head / gasket failure and are there any special tools / procedures req'd for head replacement.

Thanks for your help,
Bob

 

[SidecarFlip]

Pressure tester on the rad (avaliable at Harbor Freight) but if you overheated it, I'll bet cracked head or bad head gasket.

 

[Jim L.]

My problem is that it Has been using much coolant lately [@1/2g/hr]

No white smoke, oil is ok, but it did overheat last year.

Pretty much sounds like a crack in the head. Visual inspection is best.

Procedure will be in the WSM (workshop manual). Other knowledge of standard mechanical procedures such as cleaning of surfaces, assembly lube, head bolt lube, etc.

Special tools would be a calibrated torque wrench for head bolts.

Valve spring compressor tool. Otherwise standard hand tools.

 

[North Idaho Wolfman]

Yep Jim nailed it!

 

[rfoxinc]

Thanks everyone for the advise=

WSM found on ebay for $30
Country Sales & Service, OH has a compete head @$1000+ $90 gasket kit.
ebay has heads [from China] for way cheaper, but I'm not gonna chance it.

 

[North Idaho Wolfman]

WSM on Kubotabooks.com = Free or a small donation to them!

 

[rfoxinc]

Thanks, North Idaho Wolfman, you saved me $30.

As an update, Advance Auto loaned me a Radiator testing kit [no charge]
I pumped it to 15# [warm engine]and 20 minutes later it went down to 12#.

And of the 22 attachments included in the kit, none fit my cap!

 

[007kubotaguy]

Hello.
Just my two cents worth. I would also think you have a cracked head. I dont see many head gasket problems. I would also do a compression test before you open the engine up. Then you will have a better idea of the condition of the pistons and rings. I would not use any thing but a genuine Kubota head gasket. Good luck.
Lance

 

[rfoxinc]

Total nightmare!...It was a cracked head...and I mistakenly opted for an "OEM quality" = NOT gasket kit.

The head gasket was ...054 and combined with the .008 shim that I didn't need dropped the compression to 325# witch made starting nearly impossible and created big blue smoke clouds until it got warm.

After another teardown and replacement with a TRUE OEM head gasket the compression is back to 400#.

Unfortunately now it's puking steam /h20 out of the filler neck...I disconnected the overflow whistle which was clogged but it is still pushing steam. My next step is to retest the cooling sys for leaks again , hopefully the rad is clogged / bad cap. and not a bum head.

The head was used and the warranty has come & gone..[another dumb move]

 

[kkk]

BTW...That whistle is 125 bucks...only 2 left in the country...still 2 ..I passed.

Is there a thermostat in these?
Only had my 3rd Kubota for 2 weeks.....B7100d..with loaderand its own seperate pump/crank drive
Shocking that there is NO water pump...But in its place is the Dynamo/generator/alternator...Who Knew?

 

[rfoxinc]

GOOD NEWS!! An update, an upgrade and a big THANK YOU!!

Hello All-
The block tester revealed NO combustion gasses present in the coolant. [so far-so good]
Upon inspecting the radiator, a leak in the tank seam was uncovered,

It was repaired, thoroughly cleaned and I replaced the aftermarket cap with OEM.
The difference in quality is quite noticeable and I feel it's worth the extra $$.

I also added a temp gauge using a 34mm [Glow-shift] adapter shown on previous posts.
The supplied clamps were pretty light so I replaced with much beefier items

But on restart, the temp climbed to 190 idling and 220 under load. = seemed WAY to high..But,
I retested the cooling system for leaks and sure enough, it held 16# for an hour. [whew]

And after a review of some other posts on the thermosyphon system, it seems that 220-225 is OK.
I mowed with it for about a 1/2 hr this AM and it topped out at 210.

Your site / members have provided info that helped me immensely in dealing with this project.
I very much appreciated the comments and insight from you past experiences.

Thanks again!
Bob Fox

 

[torch]

Congratulations!

And thanks for the update.