coolant flush??

Sounds stupid, but can someone give a outline for the procedure to flush my 96 tdi's coolant system. I've done it on older cars ... threw a T in the heater hose and used the prestone kit to back flush the system. Since I can't do that with the tdi I'm stumped. I guess it might be time to invest in the maint manual

I do it the messy way: I pull the thermostat, which should be replaced anyway, and disconnect the radiator return hose. Put the thermostat housing back on w/o the 'stat. If the gasket is the kind that goes on the thermostat itself, just use some big wire cutters to gut out the thermostat so it can't "close" and use the leftover part to hold the old gasket and seal the housing.

I run water from a garden hose into the radiator and use a chunk of hose or PVC pipe or something to let the water leaving the ENGINE to run onto the ground. (Catch the stuff with a bucket at first, until it starts to run clear.) Turn on your heater to max temperature so you flush the heater core, too.

If you want to use a radiator flush of some kind, just pour it in there with the old stuff and let the engine idle. With a TDI you may have to pull the thermostat first, though, because they run so cool when they idle. Mercedes recommends Citric Acid powder as a cooling system flush, which is probably more effective than the crap you get at auto parts stores.

When everything is flushed out I rev the engine for several seconds to blow most of the coolant out of the block. Then I drain the radiator and install a new thermostat and gasket. Finally, add the correct amount of straight antifreeze needed to make a 50/50 mix. Run the engine until the overflow tank drains dry, and keep adding the antifreeze until it's all in there. From that point on, add water until the level stabilizes at the "full" mark. Remember that the thermostat won't like to open, and that you need to open the heater core too! And sometimes the water pump will lose it's prime. You can give your car "mouth to mouth" in this situation, forcing fluid from the tank into the engine by blowing into the tank. (Yummy!)

Or, you could do all this the way you're supposed to do it if you're smarter than I am. But I don't know how that works.

-mickey

Thanks mickey, they sure didn't design the system to be easily flushed

<BLOCKQUOTE><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><HR>Originally posted by Roy Basch:
Thanks mickey, they sure didn't design the system to be easily flushed

<HR></BLOCKQUOTE>

Roy:

Mickey's advice seems dead on. The trick is getting the stuff to drain cleanly, which will not happen as there is no drain plug on the engine. When I installed my block heater last October in my 96 Passat TDI, I did the following:

1. Take off engine under cover.
2. Open the cap on the coolant return reservoir. Turn the heater switch to high.
3. Find the water pump housing, (it's located directly beneath the injection pump, follow the hose from the radiator).
4. The housing is black plastic, there is a metal clip securing part of it to the other, remove the clip.
5. Place a drain pan underneath (2-3 gallons) and carefully and gingerly pull the hose part housing away from the rest of the housing. (Remember, it's plastic, so don't force it)
6. There should be a torrent of red/brown coolant running down your arm and into the pan- Yuck!
7. You can flush per Mickey's instructions.
8. Reconnect the lower hose to the plastic housing, and re-install the clip (pain in the rear- sorry)
9. Making sure you have everything secure, begin filling the engine up through the coolant reservoir. As you live in Illinois, Mickey's recommendation of a 50/50 should be OK. (Here in Minnesota, I use at least a 60/40 solution of antifreeze to water.)
10. Filling it up can be deceiving, because it seems as if the engine won't take all of the coolant. It should take an entire gallon at first, you will then have to start the engine and watch the level decrease in the expansion tank. Immediately have some premixed 50/50 coolant available to top it off as it goes down!
11. Drive the car up to operating temperature, and check the fluid level in the return reservoir. If the red light flashes on the dash on the first test drive, just add coolant to bring the level between the "Max and Min" levels on the reservoir. The light should go out immediately.

That's all.

<BLOCKQUOTE><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><HR>Originally posted by Roy Basch:
Thanks mickey, they sure didn't design the system to be easily flushed

<HR></BLOCKQUOTE>

Perhaps VW doesn't feel a flush is necessary???

Also, how often should you change your coolant? I don't believe there is anything in the manual/maintenance schedule about it. I am approaching 100,000 miles.

Ric, does your 1998 Jetta have the pink coolant? I can't remember when VW switched to the new pink coolant. It is a long-lived coolant, and VWoA says nothing about coolant replacement intervals. However, the pink stuff is equivalent to, perhaps even IS Texaco's Dex-Cool, if I remember correctly. I think that a 5 year/100,000 mile interval would be prudent. If I recall correctly, Texaco on their web site describes a Dex-Cool additive replacement package for OTR trucks to use after some similar interval, I suppose for those who just cannot afford enough down-time for maintenance.
Of course, just because VWoA is silent on a change interval doesn't mean that such a change is unnecessary. After all, VWoA was utterly silent on timing belt change intervals for diesel Rabbits. It was my dealer who recommended a 5 year/60,000 mile change interval for the timing belt. Perhaps VWoA considers a 60,000 to 100,000 mile interval to essentially BE the working life of a car?
Of course, if you are still using the green stuff, it is long overdue for a change. Do it and your water pump, or what's left of it, will be most grateful.

[ April 05, 2001: Message edited by: cars wanted ]

Why can't you put a T connector in the heater hose and flush that way?

When you pull the hose off at the radiator using the clip -- make sure you don't lose the o-ring!!!

It fell off mine and it was leaking like crazy until I saw it sitting there on the metal under the radiator... oops.

Otherwise I concurr.

Ric's advice is perfect, as always. Perfect, that is, if you're on a short term lease.

-mickey

A few notes on the VW coolant and Dexcool. I started my quest for knowledge after I came to on the floor of the parts department at the local dealership after being told the price for a gallon (wanted to have some around for any needed topoff).

VW claims their coolant is unique and Dexcool is not equivilent. I called Texaco research labs and they said that the Texaco Dexcool equivalent coolant is "essentially the same" as VW coolant but that Texaco's coolant is not approved for use by VW. They would not be specific as to the difference or whether they were seeking VW approval/certification.

My experience with Dexcool in other (mostly GM) car's has been very negative. Dexcool DOES NOT last as advertised It creates problems typically during the late 3rd to 4th year in the car. The more I asked around the more I heard sad tales and horror stories. The general concencus was to change it every other year if you want to be safe but under no circumstances should it be allowed to go beyond 3 years. In general the problems had to do with clogging of heater cores, overheating etc. seemingly caused by a breakdown of the coolant - sediment precipitating out of the coolant. Was told by GM tech that breakdown is a paticular prob. in cars where the cap is not holding pressure and the owner didn't notice for a while during hot season driving. New cap top off system - wham - problems.

I'll be flushing mine next summer - hope Texaco has VW approval by then - anyone have a source of resonably priced VW approved coolant?

If you completly flush the old coolant out, why can't you use regular Prestone? There are several long-life coolants available, besides dexcool what alternatives might the forum gurus suggest?