well, I thought I had an account here, but it must have been deleted or i never made one, but I'll introduce myself first. Hi, my name is Josh, I have a 98 f3 with 34k on it that I love.
Now on to the problem;
I had a problem with it about two weeks ago where it was leaking coolant out of the hose coming from the water pump, usually only after i had ripped on it a little and slowed down, or when i parked it, so i replaced the hose, after waiting for a hose for 2 weeks. So I went to ride it to work today, and I got halfway there and a friend I work with pulled up next to me at the light with his gti, light changes and he floors it lol we all know what happens here, I crank on it, redline first and shift into second, then I get blasted with a spray of coolant, so i back off, get to the next light and is smoking and getting hot, fan was on but stopped shortly thereafter. got to the red mark on the temp gauge so I pulled off and shut her down, let it cool for a min, limped up to a gas station 1/4 mile away and filled it up with coolant, went the other 3 mi to work fine. went to the store on lunch just fine, got out of work, babied it and halfway home it started getting hot but the fan wasnt kicking in, pulled off let it cool and drove the rest of the way home (3 mi) before it got hot again. let it cool, filled with coolant, started it, thermostat opened, filled it again, shut it off,and it blasted me with coolant when I shut it off with the rad cap off, filled it again, put cap on, idled till fan came on, ran normal at idle for 30 min, fan kicked on as it should, revved it up to about 5k rpm, and it blows coolant out of the overflow tube, shut it off and it blows more coolant and lots of air out of the overflow. tried 2 different rad caps, same result, i can see the coolant flowing with the rad cap off, as long as it has coolant in the rad, the fan kicks on, no milkshake in the oil, no oil in coolant. so anyone have any idea wtf is going on? the only thing I can think of is one of the compression rings on my head gasket is gone but not leaking coolant into the engine, cause there's no white smoke coming from the exhaust?????? Any ideas will be greatly appreciated
thanks,
josh

 

Can only go on my experience with cars here, but there are 3 things that I know can cause that. Culprit No 1: The radiator (pressure cap) is faulty & is not pressurising the radiator properly,allowing coolant to exit via over flow tube. Culprit No 2: The thermostat is faulty & is not opening up enough to allow the proper coolant flow. Culprit No 3: There is a blockage in one of the fine pipes in the radiator that the air passes over. This can happen if the coolant is old or diluted & you get bits of rust & crap that accumulates & gets trapped in the bends of the piping.
You need to have the radiator pressure checked, no big deal, most garages have the equipment to do it & takes 5 minutes. The thermostat is easy to check, but it means removing it & dropping in some hot water & seeing if it opens. The pressure caps are as cheap as buggery & a new one won't hurt the budget.
I should also mention that not using the proper 50/50 mix of coolant, can allow the boiling temp to be lowered enough to cause boiling = bubbles= temp rise= coolant leak.

 

thanks for the reply pacemaker, The bike was skipping out of second gear last year so I redid the transmission and when I drained the coolant it looked good, and was refilled after with a 50-50 mix the beginning of this riding season, the radiator is flowing freely, the pressure cap was working on the other machine just fine, but it isn't new, so I will try a new one, and I know the thermostat is at least opening because it wasn't overheating in the driveway, but I think tomorrow I will pull it out and make sure it's opening completely, but should the rad. pressure be spiking like that when i revv it like that? or when I had the cap off any ideas why when I shut the bike off it sprayed coolant out of the filler?

 

you forgot option 4 blown head gasket pushing compression into the cooling system

 

I know its not always an indicator, but I was going a long with no white goop in the oil.
But I guess I should have also mentioned #5. A cactus water pump