RTV900 thermostat housing

I did a search, but nothing specific to my issue came up so here goes...

I have two RTVs, one I bought new and one with a bad engine that was given to me. The one I bought has a transmission/rear differential problem and since I'm more comfortable with engine work I decided to repair the engine on the one I was given and swap some other parts so I would have one operational machine.

I pulled the head and found a damaged piston and a bent rod, along with a cracked head so I pulled the replacement parts from the other machine. Long story short I got it all back together yesterday and cranked the engine and it ran great, except for a major water leak. Apparently the previous owner had not kept antifreeze in the cooling system and the thermostat housing has a crack in it. The problem is I cannot get the right hand bolt out, the head goes up against the water pump housing that is part of the front cover of the engine.

I don't want to pull the head. That's more time that I don't want to spend not to mention another $70 for a head gasket. Anyone have any suggestions?

rjglenn said:

I did a search, but nothing specific to my issue came up so here goes...

I have two RTVs, one I bought new and one with a bad engine that was given to me. The one I bought has a transmission/rear differential problem and since I'm more comfortable with engine work I decided to repair the engine on the one I was given and swap some other parts so I would have one operational machine.

I pulled the head and found a damaged piston and a bent rod, along with a cracked head so I pulled the replacement parts from the other machine. Long story short I got it all back together yesterday and cranked the engine and it ran great, except for a major water leak. Apparently the previous owner had not kept antifreeze in the cooling system and the thermostat housing has a crack in it. The problem is I cannot get the right hand bolt out, the head goes up against the water pump housing that is part of the front cover of the engine.

I don't want to pull the head. That's more time that I don't want to spend not to mention another $70 for a head gasket. Anyone have any suggestions?

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Post a picture if possible so we can see the bolt you are discussing.

while you are trying to figure out the next step i suggest you soak it in Kroil .

I am pretty sure the head has to come off to remove the housing.

Rogerwh0 said:

I am pretty sure the head has to come off to remove the housing.

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How do you think my brand new head gasket with 15 minutes of run time will fair?

aurthuritis said:

while you are trying to figure out the next step i suggest you soak it in Kroil .

Click to expand...

The problem isn't that it's stuck it's that it is too long. I assembled an engine from used parts and the thermostat housing I used has a crack in it resulting in a coolant leak. Shoulda noticed the crack because when I finally did see it the crack was very obvious. Looks like somebody allowed it to freeze.

The shop manual pretty much says you have to pull the head to replace this part. I don't want to waste a brand new $70 head gasket with 15 minutes of run time and was wondering if anyone had already figured out a workaround for this.

Head gasket might be ok? I was extremely tempted to reuse mine when I had the head off. I decided that the chance of failure was too high to risk taking it all apart again and having to buy the head gasket anyways, It really demands on the value of your time vs the chance of saving the gasket price. I read a lot of forums trying to find someone saying it was ok to reuse a head gasket. Never did find that but did find a lot of people saying it would not be ok to reuse it.

rjglenn said:

The problem isn't that it's stuck it's that it is too long. I assembled an engine from used parts and the thermostat housing I used has a crack in it resulting in a coolant leak. Shoulda noticed the crack because when I finally did see it the crack was very obvious. Looks like somebody allowed it to freeze.

The shop manual pretty much says you have to pull the head to replace this part. I don't want to waste a brand new $70 head gasket with 15 minutes of run time and was wondering if anyone had already figured out a workaround for this.

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AHHH I see what you mean here. I went and looked at my engine and it looks to me the best would be to take the head off. sorry!!

could you weld the crack in the thermo housing?

Yeah I hear you. I have an idea involving a hamer, a chisel, a hacksaw, a grinder, a file, & an exhaust port stud with nut. Tomorrow we shall see...

aurthuritis said:

could you weld the crack in the thermo housing?

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It's cast aluminum - not something that I would be able to weld cause I don't have the skills...

rjglenn said:

Yeah I hear you. I have an idea involving a hamer, a chisel, a hacksaw, a grinder, a file, & an exhaust port stud with nut. Tomorrow we shall see...

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yes i thought something like that myself. just maybe if you broke it loose first then carefully cut the head off of the bolt and then if you could work it loose somehow. then you could measure the depth and get a stud in the new housing and screw it in after you get the housing in position. what would be real nifty would be a stud that was just a little to short but long enough to catch enough threads and in the end of the stud there was a slot or an allen then you could position the nut in there and then back out the stud into the nut and then tighten up.

rjglenn said:

How do you think my brand new head gasket with 15 minutes of run time will fair?

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Don't reuse the head gasket. Run time is irrelevant, what's important is that you have already torqued it once.

Fitch

http://www.aluminumrepair.com/index.asp

maybe ^^^

Could you clean the cracked thermostat housing and smear in some JB Weld?

I really like Keifer's idea...........Can you actually SEE that crack???..........Is the fluid squirting out in a stream, coming out drop by drop, or what????............

Depending upon what you can actually see, I really like the idea of using something to STOP that leak. I once used JB Weld on a float bowl of a carb out int the middle of a Utah nowhere, and it got me back 50 miles...........It stood up to gasoline so the same thing should apply to just coolant and water..................

Again, depending on what you can find and see, perhaps widening the crack a bit with a Dremmel or small grinder, cleaning it really clean with solvent, then perhaps detergent, and finally apply the sealant/repair...........Cross your fingers and check it out the next day.....God bless...........Dennis

The crack runs almost the entire length of the housing. I really don't understand how I didn't see it during assembly, but it is way past time for new glasses. It would be difficult to repair on the engine and if I remove it then I'll just use the other one that I have. I'm really liking the stud idea so that is the direction I'm going to go. I really appreciate the discussion.

I have a thread down below about repairing that housing when the tube for the bypass hose is missing. On a '06 RTV900 I just bought, that was supposed to be running fine. I decided either the head had to come off or remove the front gearcase. The local dealer here said remove the head. I believe I am fixing mine with a brass nipple but that will not help a crack. I feel for you. I don't think I would reuse a head gasket, of course mine has 1800 hours on it.
Bryce

Okay, I fixed it and I did not have to remove the head. I bought a new gasket from Kubota for $1.80. I took a hammer and chisel and broke the old housing at the bolt hole. Then I took a hacksaw and cut the head off of the old bolt and used a pair of needle nose pliers to remove the old bolt. I took an identical sized bolt and put a nut on it and then using a grinder I ground off enough of the bolt so that it would fit into the space between the front of the head and the rear of the water pump housing. Once the bolt was short enough I took the nut off to "fix" the threads from the grinding. I then put the new bolt into the appropriate bolt hole and then placed the gasket onto the bold and slid it into place. I lined up the other bolts and threaded them into the head but did not tighten them down. After this I used a flat blade screw driver to push the bolt against it's hole and then got it to start and tightened it down. I think its being held by 4 or 5 threads but it tightened and once the others were tight it does not leak.

Kind of a piss-poor design but I'm glad I was able to make this repair without having to pull the head.

All in all the job was a success, I just wonder how long it's going to stay together since I replaced a piston & rod from another engine - but I did use the same bearings so maybe I'm good...

That was a neat trick.

Keep a close eye on it until you have it through a few thermal cycles to be sure it doesn't leak.

Fitch

I plan on working it like a rented mule today so I'll know...