1996 670 summit burning antifreeze

[cheddar brawt]

Hello everyone,

Trying to fix dads old summit, Its been using a ton of anifreeze, so i decided to pull engine, and break it down. Found exaust pipe full of antifreeze. However have not found any bad gaskets, the only thing i havent taken apart is bottom end, and im going to in a few hours. Just wondering if you guys have seen this problem before. Any suggestions would be greatly appreciated!

Thanks
C. b.

 

[Backcountry]

You replaced the head orings AND the cylinder base gasket and it still leaks or just didnt think there was anything wrong....I would replace those, button it back up, and run it and check for leakage.

 

[Zachmandu]

After double checking gasket surfaces and all of the obvious stuff, I would consider using a sealant on the head bolts. A little dab under the heads, and on the threads. I have seen some of the cylinder bolt holes in cases that were not "blind", and it may be possible that you are getting antifreeze past the bolts while under heat and pressure. May also want to have the cylinders dye-glowed for possible cracks, Maybe fine cracks near the exhaust port from a severe overheating?? Every coolant leak I have ever had on a 670 has always been the base gasket btw. I would pull the cylinders, gasket and surfaces would look fine, but I would replace the gasket anyway, and that would cure the problem...

 

[cheddar brawt]

Thanks for the great replies, I think i found the problem, originally my dad had the motor rebuilt by local snowmobile shop, ( Now out of business, i see why) when the idiot mechanic bolted cylinders down he got the bolts mixed up and put the longer ones in front two inside holes, The bolts broke holes through the case. So now im looking for upper case half, think i found one on ebay.

Thanks
C.B.

 

[cheddar brawt]

So the ebay used cases showed up today and they also have holes on the upper case half where cylinders bolt down, this cant be normal, but im not sure, does any one out there know?

 

[DWHalverson]

The back set of bolts on the 670's did go all the way through and into the case. If the cases were really tunnel ported you would have to "port" the bolt with the case so it didn't stick down into the intake. Can you post some pictures?

 

[Red-eye]

I think you had to seal the threads and the washers under the bolt heads.

 

[cheddar brawt]

Thanks for all the replies, I will seal up bolts for sure, thinking of using yamabond, same thing i use on case halfs when putting together. What would you guys use, recomend? Ive looked everything over and she looks good so it must be coming from the cylinder bolts. The cylinder bolts did not have any sealant on them when i tore down.

Thanks for all your help, I love this website

Chris

 

[Zachmandu]

Yup. I just use yamabond or similar sealant, a little bit under the bolt heads, and some on the threads. In my earlier post, I meant to say that you should seal the cylinder bolts, not the head bolts. I do not believe that Doo used any sealant from the factory.