Z Boiling over

[Billy Golightly]

Ok I've been fighting with this for a couple of days now, heres the situation.

If it runs for more then 10 minutes, coolant boils out the overflow, and around the radiator cap. It is approx 95 degrees here during the afternoon.


Impellar WAS good when I put the engine together, I find it hard to believe it could got screwed up between then and now but I suppose its possible.

No coolant in the tranny.

Coolant is in the water jackets (Verified by pulling the check plug on the side)

All new gaskets including head gasket

My dad thinks that its boiling over cause the radiator scoops aren't on it...but I find it hard to believe those dinky shrouds on the Z actually "pull" enough air in to make a difference. Is my thermostat stuck? WTF is my problem?

[85_ATC_200S]

Maybe try one of the coolant coolers out of Rocky Mountian, lol, kinda stupid suggestion, but couldn't hurt! :D

[smokinwrench]

You might try Pming 200xdriver I think he has been fighting the same exact problem on his Z, maybe you guys could narrow it down a little.

[YTZ250#1]

I took the thermostat out of mine.It's not runing hot,but I do have a small leak near the cap.I think it is a bad oring on the cap itself,but will check for sure tomorrow.

[Darius1502]

Mine boiled over at the dunes with a new impeller and 2 super coolers....

I did not even run it hard...so I don't know...

I just figured the trike is old and I should give it a break...

but if you find out it would be nice to know!!!!!!!!

[TimSr]

Start it up and let it run with the radiator cap off. Looking inside you should at first see no flow until your thermostat opens, then flow should be obvious. If you have no flow as it warms up, either your impeller is toast or your thermostat is stuck closed. I have never seen one fail in the closed position. Every one I have seen has stuck open, but I guess its possible. My personal opinion is that the thermostat is too far away from the heat source, and Id only recommend runnning one in colder climates during winter months.

Another common problem that looks like boil over is a leaking head gasket. Put your radiator cap back on. Take the seat off, and take the cap off the overflow bottle. Rev it up and watch the coolant in the overflow. If the coolant reacts by bubbling or flowing in the oveflow bottle each time you rev it, you have compression leaking through the head gasket into the cooling system. Your radiator cap is like 15psi. When you rev it with a leaking head gasket, it pressurizes your cooling system beyond that and it passes through the cap into the resevoir like its supposed to when it overheats. Compression passes through a leaking gasket much easier than coolant, so its very easy to leak compression into the cooling system without leaking coolant externally.

[Billy Golightly]

Well I went crank it up and see how the flow in the radiator was but I couldn't get the damn thing to run...Fricken weird, ran perfect yesterday. Got good spark, got fuel to the carb...float might be stuck or something I suppose. Have to pull it off and check it later this evening. Are we all in agreeance that the airscoops arent the problem?

TimSr:

I have a feeling that the later is perhaps my problem. I had the head milled down some and maybe its just coming around the gasket even though its a new one. Hopefully I can get it running again and try and find out for sure.

[TimSr]

I suspect it is too. Z's are a lot more prone to head gasket leaks than my R, and Ive found that most people have difficulty diagnosing one. It took me forever to figure it out the first time but now I can diagnose most cooling problems in about 2 minutes.

Its got nothing to do with the shrouds. They have no functional purpose on the Z (too small) and are only there for cosmetic reasons.

[Billy Golightly]

Ok I got the Z running again. I cranked it up and pulled the cap off, I saw turbulence in the water. Slowly the longer it ran, the higher the water level became. I revved it up a couple times and water splashed out of the cap hole pretty far. I don't have my remote resivour hooked up yet but I didn't see any water come out of the overflow tube on the other radiator.

Before this I tightened down the head nuts to probably about >80ft lbs. Still think it could be leaking there? I'm not sure....I guess my next step is to take the thermostat off.

[Trikeaholic]

80 Ft/Lbs? your lucky you didnt break a stud off. Aren't those supposed to be @25 max??

[Billy Golightly]

I think thats what the book calls for holic. I couldn't get a torque wrench in there so I just used a double wrench extension and tightened down real good. Honestly I think the 20ft lbs in the manual is kinda cheesy considering the amount of compression that cylinder is doing.

[Xowner]

maybe thats your problem you messed the gasket up with 80lbs of torque

[Billy Golightly]

I just tightened it down that tight today. It hasn't been like that.

[Xowner]

what happens if you take the thermostat out and put the hose together?

[TeCaTe_MaN]

are you putting any water in your coolant?

antifreeze wont boil over, use straight antifreeze and put your shrouds back on, or if it's an overheating problem then put some water in there...about 50/50 hopefully that helps

i run straight antifreeze in my tecate

[threewheelin-feelin]

maybe theres air bubbles in the lines

[smokinwrench]

Runing striaght anitfreeze is terrible as far as cooling capabilities. It is better to run straight water then straight antifreeze. Not in winter though.

I think for every pound of psi that your radiator cap is that adds 7degrees to your coolant before it boils. example 5 lb cap adds 35 degrees to boiling point. This figure is with 50/50 antifreeze mix

If the thermostate is open it will not help to remove it.

I think he solved the problem by retightening the headgasket. Did you check the head and cylinder for warpage when you assembled it.

[Billy Golightly]

I didn't check the cylinder, but the head was milled so I figured it was probably straight. I'll ride it some more tomorrow and see what happens.

I'm running straight water now and have been since it was assembled. No sense putting antifreeze in when its just running back out.

[TimSr]

80 ft lbs is not good! I think they call for 20, which rarely does the job for me, so I usually torque them about 25-27.
Overtorquing will cause 2 problems that lead to head gasket compression leakage. It changes the shape of the head, and its no longer flat but pulled down where each stuff goes through. It also does the same thing on the top of the cylinder. It creates a high spot where each stud goes in.

You can still cheak for leakage with the overflow connected. Just make sure there is no air coming out the overflow hose when you rev it.