1999 SRX 700 overheating - coolant flow inconsistant - etc

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CJN01

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Central Ontario
Hello Forum. Im Chris and live north of Huntsville Ontario. This is my first post although I have been coming here and reading periodically for years. I have a stable full of sleds around here and have owned more yellow Canadian made through the years than any other brand.....but the purpose of this post is to request your help with a 1999 SRX 700.

I bought this sled with a blown center piston a while back. Was told by previous owner he suspected water in gas was the cause. Replaced the cylinder with good used one...new piston kit...new gaskets etc. The center head was discoloured from heat when melted down. Did not look warped to me so I used it. Got it running and it seems strong. All was fine for a few hours riding then the temp light started flashing. Caught it right away and didnt get too hot.

The syptoms now:
- start it cold and coolant flows in botttle.
- with cap off lift back of sled high and bleed rear bleeder till steady flow.
- lift front of sled 1-2ft and run with cap off and bleed rail bleeder.
- engine warm...heat exchangers warm...coolant flowing in bottle.
- drive sled...all fine for 5-10 min. then exchangers start cooling and soon light starts flashing.
- remove coolant cap....no flow now.
- let it cool down completely and start up again and have coolant flow again.
- repeat bleeding etc...drive again and loose flow.
- cycle continues

Where would you go from here?
Thank you SO MUCH for helping on this one.
Chris
 
Obviously the coolant system is getting pressurized. And there's a very good chance it is at the head gasket. Did you re torque after a heat cycle and was any type of sealant used in conjunction with the brand new head gasket. IE--Copper Coat, Yamahabond etc etc.
 
Did re torque yes. Two orings per cylinder...no head gasket on this sled. No other sealant used. Just cleaned both surfaces and oring journal well and installed orings dry with no extra sealant. You suspect head gaskets (orings) and may be right. Lots of coolant movement and some bubbles in coolant bottle but since the flow falls into the coolant resovoir there must be some as I see it. How do I determine if compression is getting into cooling system? Compression test shows consistant compression accross three cylinders.
Thanks for your reply.


A couple of bucks said:
Obviously the coolant system is getting pressurized. And there's a very good chance it is at the head gasket. Did you re torque after a heat cycle and was any type of sealant used in conjunction with the brand new head gasket. IE--Copper Coat, Yamahabond etc etc.
Click to expand...
 
I hate to bring the bad news but the brass gear on the crank is likely slipping, thats why it works when its cold and once the engine gets warmed up the clearance opens up and it slips on the crank and not turning the water impellar.
 
Thanks for taking the time to reply.

Dont like the sound of this but first I have to understand it. From a SRX 700 schematic I see the impeller attached to a impeller shaft that is turned by a worm gear (maybe not the right term) on the crank that turns the worm gear on impeller shaft. Where is the brass gear? And if this is the problem what needs to happen? Was this a common problem? If so was there a Yamaha service bulletin/recall?

mrviper700 said:
I hate to bring the bad news but the brass gear on the crank is likely slipping, thats why it works when its cold and once the engine gets warmed up the clearance opens up and it slips on the crank and not turning the water impellar.
Click to expand...
 
The worm gear on the water pump impeller is the brass gear he's referring to and in order to replace it you'll have to pull the engine out and split the cases in order to put in another impeller.
 
no, the gear I am referring to is on the crankshaft, its brass and its pressed on when they get warm if its old they slip, and thats exactly what they do as you described. Youd need to have the crank split apart and replaced which is a big and expensive job if you cant do it your self.
 
Well..I need to go through steps to eliminate the other possibilities before the crank comes out. First can an air pocket form in the water pump and therefore stop coolant flow? I do recall during the cool down time periodically hearing a gurgle/burp sound that I assumed what air rising to the coolant bottle. Will a head gasket leak show in a coolant pressure test? Or is there a way to tell if compression is pressurizing the coolaing system?
 
Hello again. Hope you all had good day.

Very little time for the SRX today but want to share a few details and get your opinon.
-started the srx and deliberitly left the collant bottle a little low say quarter full.
- after warm up took it out and heat exchanger warmed up ran good etc.
- 10 min or so in exchangers started cooling and short time later temp light started flashing coolant flow had now stopped.
- after quick shut down now coolant bottle was now over 3/4 full and a light bubble froth on top.
- as we chatted about what what happening gurgle gurgle then gurgle again and now the coolant bottle was almost empty.
- now Im sure it was an air bubble started it back up but unfortunately no coolant flow yet (engine was still warm).

So where would you go from here?
 
CJN01 said:
Hello again. Hope you all had good day.

Very little time for the SRX today but want to share a few details and get your opinon.
-started the srx and deliberitly left the collant bottle a little low say quarter full.
- after warm up took it out and heat exchanger warmed up ran good etc.
- 10 min or so in exchangers started cooling and short time later temp light started flashing coolant flow had now stopped.
- after quick shut down now coolant bottle was now over 3/4 full and a light bubble froth on top.
- as we chatted about what what happening gurgle gurgle then gurgle again and now the coolant bottle was almost empty.
- now Im sure it was an air bubble started it back up but unfortunately no coolant flow yet (engine was still warm).

So where would you go from here?
Click to expand...


You're seeing localized boiling because you aren't flowing coolant. Boil the coolant and create pressure and bubbles, displacing coolant - filling the bottle.

You mentioned the cylinder head discoloration - the PO ran it with no coolant flow long enough to bake the paint.

Unless the impeller is spinning on the worm shaft, I suspect Mr. Viper is correct.

Especially given the reported problems with the crank gear and Mr. Viper's engine experience.

I suppose you might able to verify this by removing impeller cover and try turning the impeller while holding the crank still after getting it hot.

That's if you can get it torn down quickly enough before the gear cools down and tightens back to the crank.

Just a guess and something I might try if I were you. Still might not be conclusive if you can't spin the impeller (did it cool off too much?) but if you can rotate it you'll know what you're up against.

If you do fix it - get the old coolant out and replace with fresh.
 
Good tips snomofo...and along the same lines as what I am also thinking trying now. The localized boiling and air pocket caused by it sounds possible as well.

My concern about the brass worm gear on crank...no dealer Ive talked to knows anything about such a problem up here. No bulletin and no recall info history. I even called Bender Racing Canada today and he said he never saw one or heard of one srx 700 up here with that issue. He said first time for everything but never heard of it. He also said the crank issues in 1998 were a completely different issue. He told me to pull the thermostat to eliminate that factor and check the heads for warpage and bleed well.

QUESTION: should coolant be flowing into the bottle through the top hose when first started cold? Or should it only start when thermostat opens?
 
CJN01 said:
Good tips snomofo...and along the same lines as what I am also thinking trying now. The localized boiling and air pocket caused by it sounds possible as well.

My concern about the brass worm gear on crank...no dealer Ive talked to knows anything about such a problem up here. No bulletin and no recall info history. I even called Bender Racing Canada today and he said he never saw one or heard of one srx 700 up here with that issue. He said first time for everything but never heard of it. He also said the crank issues in 1998 were a completely different issue. He told me to pull the thermostat to eliminate that factor and check the heads for warpage and bleed well.

The T-stat is something that could cause flow issues but your symptom description doesn't match typical t-stat failures. It is a cheap and easy enough thing to eliminate as a cause but I wouldn't run verying conditions (road running then dropping into powder) without it.

I too might be skeptical after talking with others and not finding someone who has seen this.

But frankly, I'd put more stock in Mr. Viper's experience than Bender's.
QUESTION: should coolant be flowing into the bottle through the top hose when first started cold? Or should it only start when thermostat opens?
Click to expand...

I can't say I've noticed either way but I believe the t-stat has a bleed orifice so it may.
 
Did you figure out the problem

CJN01 said:
Good tips snomofo...and along the same lines as what I am also thinking trying now. The localized boiling and air pocket caused by it sounds possible as well.

My concern about the brass worm gear on crank...no dealer Ive talked to knows anything about such a problem up here. No bulletin and no recall info history. I even called Bender Racing Canada today and he said he never saw one or heard of one srx 700 up here with that issue. He said first time for everything but never heard of it. He also said the crank issues in 1998 were a completely different issue. He told me to pull the thermostat to eliminate that factor and check the heads for warpage and bleed well.

QUESTION: should coolant be flowing into the bottle through the top hose when first started cold? Or should it only start when thermostat opens?
Click to expand...


Hello, I have the same sled, same problems you describe above. Did you figure out what was causing the coolant from not flowing when the engine was up to temp? Did you ever resolve the overheating problem? Did you end up splitting the case and changing the brass gear? Any info you have would be helpful.
 
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