Good to hear!

 

There is another symptom which I thought was normal but maybe not... If I drive the car for a while and then turn it off - then get back into it say 15-25 minutes later and start it up again the Temp gauge moves to the 2./3 mark past the half way mark. If the engine has had more time to cool this does not happen and when I drive it will cool down again to just over the half way mark. Is that normal for it to do that.. or should it dissipate the heat better. It is like the coolant overheats after the car is turned off.

 

That could very well be a bad water pump (which would be bad). Have you ever had your timing set (including water pump) replaced? If so, when?

 

Just an FYI - mine does the same thing and I have replaced the water pump, thermostat, radiator, expansion tank and cap. I can say this.. it is a bit better in that it does not go as far past 1/2 way as it used to but still does. It cools off a bit faster too and usually gets to normal 1/2 way hash. Next summer will really be the test though.

 

I just did a bunch of work on a kids B6 (that I've been working on for two years now). I've done more work on this car that you could imagine. He recently had this same problem, so I looked into it for him. I replaced the expansion tank and cap (to make sure there was proper pressure relief). I found and fixed a coolant leak at the turbo inlet fitting and I fixed a small oil leak. The car drove fine after that, but I told him I wanted to keep the car for a few more days, in order to check everything on the car before he put it up for sale. One of the things I wanted to check was his entire timing set (belt included), but he didn't want to wait for me to do these things (although very important) because he didn't find them necessary (to him)....so I gave him his car back, he let his brother drive it around and two days later, the timing belt broke and blew the engine. Come to find out: the water pump wasn't working and that's what was causing this problem you guys are talking about. A brand new water pump can fail just as easily as an old one - and even if it doesn't fail on it's own, a seized/sizing water pump/an improperly timed/stretched timing belt could cause the water pump to be ineffective. That's the only reason (I'm aware of) that has ever caused this overheating problem. Our thermostats are not like most. They stay open (as opposed to opening when hot), so for pressure to be building up after you stop the car, that (in my experience) is because the coolant is heating up the entire time you're driving the car and when you stop the car, it no longer has airflow (and possibly a crippled water pump) helping to cool it down, so it's heat soaking, causing the pressure build up. I would strongly suggest that you guys have your timing sets checked before you end up in the same position this kid did. It won't cost you anything to check it yourself (if you can), but it could save your engine. If you have to replace your water pump, make sure you get a new one with metal impellers.

I hope that helps.

G/L guys!

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Thanks for the help... how do you check the Timing Sets (does that mean the parts or something else)? Also if the car is not overheating at all while I am driving would that not imply that the water pump is doing it's job. When I stop as described above then you will see the temp gauge rise. But if the car sits a little longer then it will cool enough so that when I start it again it will not rise.

Also It was doing this before the timing belt change and after. And also before the old water pump went bad and after the installed new one with metal impellers. But I do agree it is not correct and should not work like this. But before I change out the water pump again I really want to make sure it is it - the job is a bit of a pain. The old timing belt was still good but since the water pump went bad I changed it (of course). And the old timing belt and water pump was installed by a mechanic - not saying they cannot screw up as I have found out since I started doing all the work on the car... just commenting.

 

Checking the timing belt itself is relatively easy. Just pop off the plastic timing cover at the front of the valve cover/head. It has two clips (on the upper sides) and the water and vacuum hoses are secured to the front. Just pull those up over the valve cover. Once the timing cover is off, you can visually inspect the timing belt. Try to twist the belt. It should have enough flex to bend 90 degrees.No more.

When you're driving, you have cool air blowing into the engine bay, you also have the radiator and AC fans working. If your water pump is "crippled" (not good, but not completely dead) then it will also be moving coolant around, helping to cool the engine. When you stop, so does all of that cooling power you had. Hence the boiling of the coolant/rise in pressure.

Unfortunately, there's no way (that I'm aware of) to check the water pump itself, but what you're describing sounds very much like the water pump. You're only real option (that I can think of) is process of elimination. Start with a full cooling system flush (including cleaning your heater core): Do the heater core first. What I do, is take the heater core return lines off (there are two lines that go into the firewall - both need to be removed). All you really need to worry about is the one on the left. Take off the coolant reservoir cap, remove the heater core hoses and get a Shop Vac. Put the Shop Vac onto the (left) pipe that protrudes from the firewall and suck as much **** out of there as you can. Once done, replace the hoses.

Radiator flush is as follows: With a cool engine, drain all of the coolant. After that's done, fill the reservoir tank with tap water (a garden hose works well) then start the car, let it idle, bringing it to operating temperature, with the heater on full blast/full heat. Add water to the expansion tank as necessary. Once the cooling system is full and has a chance to circulate, shut the car off and repeat the procedure two more times. Once all of that's done, fill the cooing system with anti freeze and Distilled water. That should give you good coolant systems circulation.

Try driving the car for a day or two after that and LMK what happens. If that doesn't solve your problem, we'll go from there.

G/L

 

Thanks for the post. When I installed the timing belt I checked and I am almost certain the flex was around 60 degrees maybe a bit more. Definitely not grate than 90.

Question. is it normal for the coolant to rise in temp and pressure after the immediately shutting off the car where it will register on the temp gauge after 15-30 minutes?

Regarding cleaning out the heater core I did it twice.. not as you described but by attaching a hose and turning on the watrer to flush it out both directions utilizing the inlet and outlets. I then flushed the entire system like you described Filling the system then running it and then draining it. I even drained the block. I then filled it up with coolant and distilled water. The reservoir remained pink and fresh looking until we had one cool day here and I wanted to test the heater. The heater has not blown hot for a long time. The outlet and inlet line is hot but the core must be plugged or ??? Anyway after running the heater (it only blows warmish at best) the coolant color turned darker and looks a dirty - not as bad as before. So the heater core mush still be a not right. Even before I ran the heater when the coolant was pink and clean I still have this issue - but the issue mostly shows up when it is hot out. By the way why do yo need to remove the reservoir cap if both the inlet and outlet lines of the heater core are remove. The system is disconnected.

I am going to test something. Run the car for 30 minutes at 65+ mph on the freeway then shut it off and check the gauge every 5 minutes to see the change.

As far as the heater core goes - I was afraid to put too much water pressure through since I did not want to blow it out.

Will update again after the freeway test.

 

It is completely ABNORMAL for the temp to rise AT ALL after you shut off your engine. Same goes for pressure (it should not rise above normal at all). Stop doing that. Your "tests" are going to ruin your engine.

When I talk about cleaning the heater core, I say "take the reservoir cap off" because you don't want to have any pressure in the system when you take your heater hoses off, unless you want one of them to blow up in your face (since you obviously have a pressure build up somewhere). It just a matter of being safe than sorry.

The method you used to previously "clean" your heater core is not very effective IMO. By disconnecting both heater hoses and using a Shop Vac on the outlet (left side pipe), you can put a ton of suction on the outlet pipe, with little concern for damaging the heater core, whereas flushing it with water (through the inlet pipe) can cause a leak/failure of the heater core (because you're putting unnecessary pressure on the heater core). That would be very bad, as you have to remove the entire dashboard just to replace the heater core.

The fact that you say your coolant keeps getting dirty and your heat doesn't blow hot tells me that your heater core is still clogged. That could be a good thing, because that may be your problem after all. If there is pressure building up in your heater core/hoses, that might explain your temperature and pressure problem.

Like I said: Start with the simplest (and cheapest) things first. Flush your cooling system (per my instructions) and thoroughly clean your heater core (first/separately). You might just fix all of your cooling and heating problems for twenty bucks. That would be a whole lot better than unnecessarily replacing your timing set.

LMK how it goes and G/L.

 

Great information ... thank you. Fortunately it is cooler now so the car does not exhibit this issue much. By the way I have not done any tests yet just normal driving.

I will let you know how it goes as I get to it.