Riddle me this!

austin26372

austin26372

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I searched but I feel this is a special case...

I bought my new to me 145k mile MK8 last Saturday afternoon. I drove it around town and back and forth. Popped the hood and noticed the belt needed replacing "I'll have at that Monday". Off I went Sunday for work as a pizza delivery driver and sure enough, the belt shredded to bits. I drove a distance of 1/2 mile after the belt tore (to get to a safe spot). When the tow truck arrived I noticed a fair amount of coolant on the ground.

I sent the car back to the dealer I bought it from and he replaced the belt. Drove it to work the next evening with the low coolant warning, but she ran fine and at proper temp. The next morning I filled the coolant back to the cold fill line; it was about 1 gallon short, and off to work I went... didn't get but 2 miles down the road and she was running very hot. Some more coolant was spit out, so I let it cool off and proceeded to my mechanic.

The mechanic did a compression test - results showed a slow leak. Holds strong at a low point of 14 psi, though.

Rinse and repeat.

So, recap: run with full coolant = overheat. Run a gallon short = runs just dandy.
 
i agree, had same problem with mine at 144k. then one day inoticed a puff of white smoke coming out exhaust, a tell tale sign of water in cylinder.i tell youi bought themogasket off internet, followed instructions, never had a problem since, its been a yeari put on headers full exhaust, mass air, programmer since then, noproblem. they have a guarantee if itdoes fail, they will pay for repair. they have a 98% satisfaction rating, check it out.
 
Are you sure you are filling and purging the system correctly? Coolant should be added thru the cross over tube.
 
Roadboss said:
Are you sure you are filling and purging the system correctly? Coolant should be added thru the cross over tube.
Click to expand...

+1, fill while hot, not while cool. Start out with it cool and cap off. Can't go by the fill line until you know for sure you have burped the cooling system yourself and actually seen it and know it. The cross over tube cap is the highest point and that's where it needs to be filled. Make sure all air is out of the system completely, replace cap and then see what you have after that. Don't even bother with the cap where you see the fill line at. Leave it on.

If you keep running hot with city driving, then yes, I would say you have something wrong. Could even be the thermostat, bad water pump. You'll know if the pump is bad while you have the cross over cap off. Water will be rushing through and popping out of the hole but get that air out. Make sure your cooling fan is kicking on too. Unless something bad is wrong, they normally don't run hot with city driving like they would with HWY speeds.
 
Don't think the worst immediately. Chances are most of these mechanics don't know how to properly add coolant to these cars. Adding coolant to the reservoir will just boil and evaporate. Do you know how to remove the crossover cap?
 
1/4 drive breaker bar.
if it's stuck, might need pb blaster or similar. or a torch. heat the pipe around the bolt, not the bolt directly.
 
I know it is also tough to see... but these cars have an aluminum radiators w/ plastic end caps. These leak over time. Try and pinpoint where your coolant is landing and try and see if you can see a drip path. Should lead you to the bad part.
 
Okay, an update. I pulled the crossover cap and filled her up (took almost a gallon). Hopefully this should eliminate air in the system.

I was told to take the cap off the reservoir and idle the car for about 15 minutes with the heat on to eliminate air completely - can anybody confirm this as a viable solution?
 
austin26372 said:
Okay, an update. I pulled the crossover cap and filled her up (took almost a gallon). Hopefully this should eliminate air in the system.

I was told to take the cap off the reservoir and idle the car for about 15 minutes with the heat on to eliminate air completely - can anybody confirm this as a viable solution?
Click to expand...

Either way works but you'll see it spitting out the cross over tube when it warms up and that's the air releasing. I have never took the cap off the reservoir but I guess it can't hurt anything. Take it for a test drive on the HWY at 70 to 75 mph for a good stretch and see if it acts like it's going to run hot. If it does, you might not have all the air out, OR something else could be wrong.
 
Got her up to operating temp and out on the highway. Runs fine without the slightest hint of wanting to run hot. To be sure, I also went out and sat in some slow moving traffic and varied my speed. All seems well!!
 
Even once "burped" properly, check it one final time after sitting overnight!

Leave the reservoir cap on and remove the cap on the crossover tube. It should be full. If not - top it off. Replace the cap. DO NOT remove the reservoir cap before checking the fill level at the crossover tube!

THEN check that the reservoir is at the Cold Fill line. If it is below the Cold Fill line, remove the reservoir cap, fill to the line and replace the reservoir cap.

If any coolant is added at either the crossover tube or reservoir, run the car up to operating temps and repeat this check the next morning. Repeat until it passes this final check! ;)
 
Thanks for the final tips JP! I drove about 110 miles tonight with work at all sorts of speeds and she did fine. Heck, I even ran around with the AC on for half of the time!
 
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