does anyone have a spec or know how far the thermostats should open on the 9U tractor?

Ours is overheating and will cool down in a few minutes, but it's hard to get anything much done spending 1/4 of your time idling.

fan belt has been tightened, externally the radiator core is open when you look through it and coolant circulates through the radiator. I used some muratic acid to acidify plain water to flush the system with and it seemed to get a lot of mineral out because the water drained very cloudy and a lot of solids settled out over time from the sample I kept. I used perhaps a pint in the whole cooling system and circulated it well several times over a couple of days before draining it and flushing with pure water.

When we tried it out this morning, it stayed cool enough to run perhaps 5 minutes longer than before.

I wasn't able to remove the thermostats (no retainers on these) without drilling a hole in the rim and prying them out of the housing, so I filled the radiator until coolant was up around the thermostats in the housing and heated the housing with a torch until they thermostats opened. One was open perhaps 1/2" and the other 3/8". the open disk can be pried farther open against the spring that keeps them closed, but that was as far as I could get them to open by themselves. When you pry on it, the disk lifts off the stem of the thermostatic bulb.

Has anyone found a good "rod" to clean the flues with? I know some of the bolts will end up rung off in the top tank if I remove it to rod out the core, but that may be next unless the thermostats could be the problem. I was mainly doing the acid soak to soften up the mineral prior to rodding out the core, and just hoped it had made enough difference to help the overheating without the rodding

Also, has anyone noticed that there's nothing under the radiator to keep hot air from recirculating down into the belly pan and back through the radiator again. this has a factory pusher fan on it with factory shoroud, just missing the wire guard on one side, the shroud is complete. I'm wondering if blocking the space under the radiator would make much diffence.

Thermostats should open @ 166 - 170 degrees F. and be fully open @ 183 deg. F. I don't really know what that translates to in dimensions.
They also can be disassembled and cleaned. If they don't test out after cleaning, it's time to replace them. It's also possible to replace them with automotive type that has the large diameter flange.

The R series D6 had a baffle out front to discourage air recirculation but was done away with on the "U" models.

I use an old band saw blade with the teeth ground off to rod my radiators.

There is always different things causing overheating but if there is any doubt with thermostats then get rid of them and install new ones as the expense of ruining an engine is much higher than replacing two thermostats even at there high price.Compression getting into the cooling system has always been a problem for coolant to circulate correctly.Also make sure the relief system is ok too.My first test and worked so many times was the leak down test by pressurizing the system at about 15 lbs. & shut the air off & observe the leak down & this could tell you alot if compression is getting into the system from say a bad head gasket, cracked head or prechamber or low liner etc. so you knowed you had a problem so you had to start looking.

One of my favorite checks is just to top off the radiator and check for bubbles while running.

Yes OM that is a good quick first test & also can tell you alot but is best if the engine is warm. I have seen it so many times while dyno testing engines that there was no bubbles in the sight glass till the engine was hot & running under load for some time then the bubbles would start to appear in the glass but some with serious problems would start right away.The dyno we had had a big heat exchanger for cooling & cool water from the building supply was run through the cooler & flow adjusted as needed for the cooling.

I was getting some bubbles yesterday and spent some time pressurizing each cylinder to try to see which one might be leaking. with the fittings I have, I show 110 psi at the gauge, but I expect with the restriction of hoses, the piece of old injector line and the torched injector valve, the pressure in the cylinder was a lot less than the gauge. I never could show any bubbles in the radiator. Radiator cap doesn't seal at all, just keeps out the bugs and sticks. I put a new rubber seal in it late yesterday, but haven't run it enough to know if it will keep pressure in the system.

While I was checking each one, I found that the flywheel marks didn't put the piston on TDC well enough to keep the engine from rotating. Finally put a wire down each one to find TDC and had no more trouble. Is there some advance figured into those marks on the flywheel, or is that supposed to be TDC?

I hadn't thought about a bandsaw blade, the only ones I have are too wide, but I think one of my employees has a small woodcutting bandsaw that uses narrower blades that might work. How hard are the bolts on the top tank/core flange to get loose? On the thermostat housing, out of 6 capscrews I wrung off one and heated another to get it loose. Any tricks to the rodding?

Yes those marks is for TDC for the pistons so don,t know what the problem is unless the flywheel is not on right according to the marks on the crank & the flywheel.Most later engines has one hole off center so the flywheel can only go on one way, the right way.

If you want accuracy for piston position, set up with a dial indicator probe down through the injector hole (probe dia. just under 1/4 in.) Use a collar so the probe doesn't get dropped.

I use a section of metal cutting band saw blade (3/4 wide x .030) Round the corners off so you don't snag the tubes. Any blade that fits will work after grinding off the teeth and get width to suit.

Those tank bolts are high risk breakers, especially if they have been there a long time with no anti-seize.

I just finished rebuilding my radiator, I had to take it apart to have the bottom tank welded from where the person whom I bought my cat from let it freeze and bust. To get it apart I kept spraying all the bolts with WD-40 each day for about a week and they all came out ok. I had a few heads that where so rusted that the heads where rounded off. I went to Sears and bought some "bolt head e-z out sockets" and they worked beautiful on the rounded off heads. I didn't have a band saw blade eather so I used a old 12" hack saw blade and worked from both ends and flushed with a garden hose. After I got it apart I used a "tap" to clean up all the threads befor I went back together and it sure made things go back together a lot easer. I used a "Die" on the bolts to clean up the threads and replace all the lock washers. When I put it back together I torqued all the bolts to 30 foot lbs about three times all the way around. Leaked checked and it held water good.

CCJersey, what do you mean? I don't have my parts book close, but are the retainers the brass tapered rings that drive down above the thermostats till flush with the thermostat housing?

I wasn't able to remove the thermostats (no retainers on these)without drilling a hole in the rim and prying them out of the housing, so I filled the radiator until coolant was up around the thermostats in the housing and heated the housing with a torch until they thermostats opened. One was open perhaps 1/2" and the other 3/8". the open disk can be pried farther open against the spring that keeps them closed, but that was as far as I could get them to open by themselves. When you pry on it, the disk lifts off the stem of the thermostatic bulb.

I assume yours are like mine? When I pulled mine & waterpan/heat tested they would start opening around that 160+deg & was fully open by 180-185F & seemed to both be fully open at about 3/8"plus as I recall. And like you, I pry disk against spring etc they opened a little farther & same stuff you saw.
But, when mine cooled down & closed, they seemed to not totally, fully close....just gapped slightly. I checked several times.
And BTW, that bulb seemed to be down inside at bottom of thermostat & expands & pushes shaft up to open disk.....I had mine disassembled...spring unhooked & threw one in pan to heat up to test. When it was put back together & cooled it didn't want to close nearly at all. I thought it was toast...I think the bulb expanded too much.
I heated & cooled 3-4 times, then it started closing OK.
Below, I wrote about how I played round & tweaked them.

OldMagnet, after you tempted me about the automotive thermostats couple months back, I checked with every parts store here in C. Oregon for automotive thermostats that would fit & was never able to find anything size wise that wouldn't fall thru. I measured OD & ID of housing hole & thermostats to see what would fit & stay put under the retainer ring.
I don't have my notebook here where I wrote stuff down, but as I recall OD of my thermostats was about 2.940" or so, & smallest I figured would work was about 2.750" or so.
BTW, automotive thermostats are lotscheaper than Cat!

& BTW also, this is kinda different, but anyone out there got a lead on a hotter thermostat than 192F that Ford/IH puts in their 7.3 IDI? Few months ago I was told that Ford carried a 205F that would fit a bigblock (460) & fit the 7.3. I checked to no avail, & nobody, Ford, GM, Dodge has one I can find.

Anyway, couple months back, before I got sidetracked with Dr's playing round with my innards, I posted about my problem of my 9U not getting hot enough,especially because I was trying to set mine up to run WVO & I needed hotter heat to heat the oil before injection. Correct engine heat also helps eliminate internal engine coking.

(usually heat problems are from overheating, & here I am with not enough heat!)

Working mine I was maybe getting to 120-130Fcoolant & was running 55-60 oil PSI. Unless I covered radiator etc even in warm/hot weather. When I finally covered stuff & worked it I finally got temp up to 170-185...then oil PSI dropped on down to about 35-40PSI.

(I used to watch everyone's posts about oil psi running 20-30PSI & I thought I was hot stuff & had a really tight 9U, now I think I wasn't so hot afterall..haha)

Anyway, I flushed the system, which as it turned out to be really clean afterall I think, changed temp gauge, which ck'ed same as old gauge, pulled thermostats & ck'ed them. I pulled them apart & cleaned & polished that shaft & stuff. Put 'em togerther & they tested better, but still seemed to not want to close totally. I reinstalled, but still had too cold problems.
Pulled them again & finally decided I was at the hissy-fit & 10# sledgehammer point & couldn't hurt anything anyway, so I ground about 1/8"-3/16" off shaft, put back together, & it start opening at 160-165F as before, & fully open at 185F. But now It closes totally when it cools.
I re-modified both of them & reinstalled in engine....now I'm finally getting hot....180-185F working, but have really only ck'ed it once or twice.

I also got my WVO set-up going on this thing, but still need to finish tweaking with a few things. It never misses a beat when I switch over to WVO from diesel.
I took pics of everything, but got really sidetracked & want to finish, before I post it all.

If I was able to run this thing right now, it's so dry & windy water would have to be sprayed & sprinkled....neighbors, City, County,...seems EVERYBODY wants to write Dirt Blowing Tickets......& I don't want to squirt water anyway!!!

siggghhh.......