SX 700 Engine issue

mtnmaxman600

mtnmaxman600

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I have been helping a young man on his SX700 and well he is still having an issue with it overheating. My guess is that while its running there is compression gas getting into the coolant system and aerating the coolant and pushing it out the overflow bottle my question is if the water pump seal make this happen or is it more likely a head gasket issue. To the best of our knowledge the sled has over 10,000miles and has NEVER been apart. The thing runs like a champ and it doesnt start overheating and pushing coolant out untils its been ran for 20 mins. Any Ideas I told him that the best thing he could do is rebuild the engine but to be honest not sure if the sled is worth it last owner was kind of hard on it and butchered some of the stuff up to lighten it up for racing.
 
Ya I had same issue sounds like a crack in the head gasket. Put some new rings in it new gaskets and good to go.
 
I suspect you might have a warped head, If so simply mill the head. .020 will take nearly all warpage out plus boost up the compression. Note, if you do mill the head, leave all 3 layors of the head gasket intact. Good luck Al
 
x3 on head gasket issue. As far as I know the water pump seal being bad wouldn't introduce compressed air into system, I tend to think if it is/was bad it would just leak.
 
First off, big thanks to the kind man Eric (mtnmaxman600), who did a huge amount of work on this sled with me! ;)! My names Taylor, I'm the owner of the frankenstein/butcher sx. I was about to make a thread about this but he beat me to it. Anyway, I bought it a few years back now for reasonably cheap. It's always ran quite well and I'd like to keep it but It has it's issues for sure. I just ran it for a bit until the temp light came on to feel the exchangers. They were all warm to the touch (running boards and rear one) The overflow wasn't bubbling this time as it was hot. I'm really not sure which route to go next. Eric and I put in another proaction skid as the old had bent rails and the broken weld in the "W" arm which is common I guess. I'm leary of ripping into it too much without the proper knowledge and help. Any help or advice would be greatly appreciated. I can answer any questions anyone has. Thank you everyone! :rockon: IMG_3701.jpgIMG_3704.jpgIMG_3705.jpgIMG_3706.jpg
 
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Head gasket isn't that expensive and fairly easy to change. more than likely your problem agree with Devlin no compression in the case so it wouldn't push through the seal. If it was bad it would more than likely fill the crankcase with coolant.
 
dblshock said:
would a compression test expose the leak?
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Typically no, would have to be a HUGE leak to notice it on a comp gauge, Being as it takes 20 minutes to start over flowing coolant I say it wouldn't. It would show up on a leak down test but leaking rings could muck up the results. Either way head should come off for an inspection. I would check squish prior to tearing it apart (solder method) and then inventory the gasket (is it a whole gasket or already missing layer) Check head for warpage and go from there. If warped mill per previous mention.
 
What is squish and the solder method? What do I need to know before pulling the head so I don't wreck anything else? Thanks!

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You bend some thick solder (I use copper pipe solder) into a 90° and put it down your plug hole make sure it is parallel to the wrist pin then rote the engine buy turning the primary. When you feel it get tight you are touching the solder you will have to give it a little harder turn to crush the solder. When your past the hard spot pull the solder out and it should be flattened take some calipers and measure it. as far as pulling the head just drain your coolant unhook the upper rad hose and ect and take the nuts off. There should be three layers to the head gasket. Unless someone has removed the middle layer.
 
Have you made sure that the impeller just isn't striped on the shaft..... this is an aluminum impeller on a steel shaft.....
 
No I havnt opened it up yet. It seemed to maybe have too much coolant and now I need to run it and see if it will get hot again. This all started after I discovered a mouse in the overflow. It began getting hot then.

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chris700readhead said:
Its probably just an obstruction in the cooling system if you found a mouse in it. it helps if you tell the whole story. Who knows what else is in there.
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X2 on this tid bit of info changing the scenario. Had you ran it prior to finding the nest? Cant imagine the passages on an exchanger are very big....couple of mouse turds or some nest could plug things right up. Before tearing into motor I would check flow/restriction in the exchangers. You can pull the bumper cover off and pull the rubber hoses off to isolate each side/rear exchanger. Once you have pushed the coolant out you should be able to blow air threw them relatively easy. I would push air opposite direction from coolant flow, might be able to add water and push it all out and just be a bunch of time and minimal parts needed.....other than needing new anti-freeze.
 
The overflow didn't have a cap before and while it sat two summers ago a mouse crawled in and drank itself to death and ended up in the very bottom of the bottle. I didn't see it and ran it a little the begging of last season until it started getting hot. I looked into it and saw hair floating through the bottle. Fished him out and topped it off. It continued to overheat so I put it away until Eric has helped me. We drained and flushed the system clean. It never got hot before the mouse incident. Thanks again for all the comments and advice guys. Appreciate it!
 
you can tell real easy if the headgasket has been peeled, just look at the little tab that sticks out in front between the head and top of cylinder, it will have a littlerivet holding the 3 layers together, if the rivet is gone someones been in there before.

the head gaskets are $30 each for a sx so thats $90 for 3 new ones, i wouldnt rip them apart if you dont need to!

so all 3 sparkplugs look the same?
 
I replaced all the plugs today. Old ones all look dark with a little brown color to the electrodes. Pretty normal I guess. As far as the head gasket there are little brass colored rings on each of the tabs that extend out.
 
teggy13 said:
I replaced all the plugs today. Old ones all look dark with a little brown color to the electrodes. Pretty normal I guess. As far as the head gasket there are little brass colored rings on each of the tabs that extend out.
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then the headgaskets are stock and have never been peeled, because you have to grind off those little rivets to seperate the layers.
 
That's good I guess. Thanks Mr viper. Looks like I'll be pullingthe head to see the gasket sometime soon. I'll post pictures on here for everyone to read the condition.
 
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