Cooling System Fill/Bleed

[topless96]

Looking for a link to the proper method of filling a cooling system after engine install. I remember reading some folks had a problem with it (air bound) and my friend is installing a motor I rebuilt for him. I described my method but would like to see other experiences. Thanks in advance!

[topless96]

no, a 1996 jetta tdi

[Rabbit on Roids]

lol, he must not know the difference. thats alright. might want to try checking the TDI section if you have a TDI. lol, but that makes too much sense.

[topless96]

Sorry but it has a 1.6 that I modified and rebuilt for him. The 1.9 spun a rod and went through the block.  !.6 was cheeper and available. What is the big difference in bleeding the system. They both seem to have very similar hose hookups. Guess my assumption that the IDI boys were friendlier was wrong! 

[Vincent Waldon]

Guess my assumption that the IDI boys were friendlier was wrong!  

And now we're super-motivated to help.

The IDI, TDI, and Vanagon are actually slightly different each in their own ways... t-stat and/or associated plumbing is in a different spot and the nuances of bleeding are also a bit different.

So lets start over... what exact engine are you talking about (you say TDI in one spot but mention a 1.6 IDI in a different post)... and we'll go from there.

[topless96]

its a 1.6 turbo . not sure the year but is a turbo not a NA. His car is a 96 Jetta was a gaser but then someone put in a 1.9 turbo from a Passat. 1.9 Died and I did the 1.6 for him. Installed but not totally hooked up. I mentioned to him that he should check into doing the cooling system but he said the other setup never overheated. just want to see him be successful with this motor.

[Rabbit TD]

I've always just filled the reservoir letting it slowly fill on my Rabbit 1.6's I've had.  You can pull the top hose off the radiator also and pour it into the hose to fill the block.  I've never had any problems with air in the system other than from blown head gaskets.

[53 willys]

let it run with the cap off until the t-stat opens...once the t-stat opens fill it up and let it burp the air for a few minuets...now put the cap on and enjoy.
if you end up with air pockets and weird temps then maybe try some creative burping....

[Rabbit on Roids]

i have never had a problem bleeding a VW car cooling system. a van would be a bloody *** tho.

[theman53]

This probably isn't recommended, but I usually drill a small hole in the T stat. I can't remember what but I believe a 3/32" hole in the flange part. It probably corrodes shut eventually, but it will help to get the air out and won't overcool the engine either. I got the idea when I bought a "performance" T stat for my 400 Ford that kept overheating. It had about a 1/4" hole with a brass rivot that "floated" in that hole. When the pressure tried to go backwards the rivot would shut and when the water pump was pressuring the system it would "float" opening the hole. So now I just drill a smaller hole and no problems yet. X2 on leaving the cap off so no pressure builds up on first start.

[truckoSaurus08]

I like to squeeze the upper radiator hoze a few times with the cap off of the reservoir and then let it warm up. Usually works for me.

[Rabbit on Roids]

I like to squeeze the upper radiator hoze a few times with the cap off of the reservoir and then let it warm up. Usually works for me.

x 2

[Vincent Waldon]

On IDI engines I usually:

- disconnect the upper rad hose and fill the rad thru the hose.  This ensures coolant is on the other side of the closed t-stat
- re-connect the upper rad hose and fill the block via the coolant reservoir
- start the engine and run it with the coolant cap off, until the the lower rad hose starts to get hot (signaling that the t-stat has opened).  Might have to add coolant as the engine warms up.
- let the engine cool overnight
- top up the coolant and replace the lid
- enjoy.

[topless96]

Thanks all! He used the upper hose fill and added coolant slowly. Burped quite a bit and then came to a final level. One problem is a mechanical temperature gauge he put in the upper pipe where it goes in to the head does not seem to even move. Could be a faulty new gauge as both radiator hoses get hot so he must have flow.