Boiling ATF

Jeff54Griffin · 12 February 2012, 01:57

I took my 69 CAS out for a long run today for the first time since the engine rebuild and conversion. At about 35 miles into the trip it started acting a little sluggish. I stopped and looked under the bonnet and all looked normal and was running quite sweet. I looked under the engine/transmission and all looked normal. There were no error lights showing on the speedo. I continued on to my destination just driving slower. When I got there I checked the engine compartment and underneath again but all look normal, so I shut it off. Thats when I heard the sound, wierd, a sound like boiling water. I opened the bonnet it again and with the engine off I could clearly hear the boiling sound coming from the ATF tank. When it cooled I check the volume and it was normal and the ATF was its normal red color.
Obviously the ATF FLUID TEMP SENDER IS NOT WORKING. What should I check to find the cause of the overheating fluid?
Thanks,
Jeff

68autobug · 21 February 2012, 12:34

Well, I have never heard of that before..
Was it filled up with DEXRON automatic transmission fluid.?
If it was filled with another type of ATF, it may not have the high temperature or flow features of DEXRON ATF...
I presume You checked the oil level in the engine.
The ATF should only overheat if the car is heavily loaded and going up a mountain road in DRIVE 2
then the light should go on which means to go to DRIVE 1

so, If Your car wasn't heavily loaded and You weren't going up a steep road...
only thing I can think of... is something restricting the flow of atf..??
strange that one...
Hoses the same size as original.. ? fittings the same size inside?
large hose for the return of ATF...?

The ATF was red? no frothing? no water in the ATF??

LEE

Jeff54Griffin · 22 February 2012, 02:45

Yes, it is filled with Dexron
Oil level normal in both engine and ATF holding tank.

I had the hoses replaced with new and used the original fittings- so I don't know if they are the same as original. Can I purchase new hoses/fittings that are correct size?

ATF is solid red, no foam, not pink. No Frothing and no water

68autobug · 22 February 2012, 11:35

Hi Jeff
it may not be the hose itself, it may be a connection..
were the orignal fittings used on the hoses?
as if new fittings were used, one of th fittings may be restricting the flow of ATF..
I used to sell hydraulic hoses etc many years ago and the internal clearance in hose fittings was different in most different makers... even though the fittings are sized by the Inside Diameter
1/2 inch means the size of the hose is 1/2 inch... but the fittings vary in size greatly..
If the original fittings were used... then I can't come up with anything yet..
It definately seems that the ATF was NOT boiling or over heating.. was the correct color etc.
You would have noticed that the pressure hose is smaller than the return hose which is larger for an easy return of ATF.. into the tank..

Lee

Jeff54Griffin · 22 February 2012, 15:14

Thanks, Lee.
All fittings are orginal, only hoses are new.
ATF was boiling, at least boiling sound and when I turned it off the ATF boiled out of the cap onto the ground.
I am going out of state for a week and when I get back I am going to take my fuel pump and pump fresh ATF into the system and see if any junk comes out. I also need to replace the temp sensor as it is not working.
Jeff

CarlIseminger · 22 February 2012, 18:59

When you mentioned it boiling out of the tank out of the cap, did you actually touch the fluid to see how hot it was? The way you describe it makes it almost seem like the fluid was "whipped" into a froth, incorporating air. This will expand the fluid so it would overflow the container when stopped.

68autobug · 23 February 2012, 05:33

Quote from: Jeff54Griffin on 22 February 2012, 15:14
Thanks, Lee.
All fittings are orginal, only hoses are new.
ATF was boiling, at least boiling sound and when I turned it off the ATF boiled out of the cap onto the ground.
I am going out of state for a week and when I get back I am going to take my fuel pump and pump fresh ATF into the system and see if any junk comes out. I also need to replace the temp sensor as it is not working.
Jeff

Hi jeff
OK.. new hoses but original fittings so I don't think they are the problem..
and it was boiling.. or boiling sound and boiled out of the cap... onto the ground..

or was it aerated... air in the ATF..

something we hadn't thought of.... the pump...
was there enough ATF in the tank? so the pump was sucking in air?? from the tank..
as its really a sealed system.. I would take the ATF pump off and check it..
the gears can score the plate but the plate would need to be badly scored to lose pressure..
there is also a pressure relief valve in the pump. also check it to see if the spring has broken..

so, Your hoses may be OK... maybe a bit of gunk in the ATF??
but I'd check Your pump first...
Hoses and fittings should be OK... ?? unless a fitting has been damaged when being installed..
Banjo bolts.. fitted correctly? ATF pipes not damaged?? restricting the flow..?

I'll keep thinking

LEE in Australia

Jeff54Griffin · 02 March 2012, 01:23

I was in error when I reported that my fittings were original. One is not, it is completely different than the other stock fitting. Is there somewhere I can buy a new set of hoses with stock fittings???
Jeff

68autobug · 02 March 2012, 10:03

Hi Jeff
I don't think they are available..
I have heard of people getting new hoses made up, even with new fittings
including the banjo bolts on the bell housing...
which I thought would have been the hard ones to match..
but as I said, change brands and they can be entirely different..
even though they fit OK.. but all the VW parts may have been special parts
with exacting holes in them.. made to do one job...

I'm guessing the inside of the "new" part may be restricting the flow of ATF.. can you tell me which part it is?

then again, it may be something else..
You will probably find a used hose on the samba..
with the original ends OK... and have it remade up...
the hoses are matched.. with the old ends.. and new ferrules used to hold them onto the hose.

or have the flow rate checked with it and the replacement hose You have..

I only know that the pressure side has small hoses and fittings and the return lines are larger so the flow of ATF
isn't restricted.. You can try running the engine with the ATF tank cap off...
and see what happens... although the return port there is close to the top of the tank neck
and may spurt ATF everywhere.. ??

I used hose clamps on the Pressure hose in the engine bay..
good quality hose clamps naturally...

cheers

Lee in Australia

Jeff54Griffin · 02 March 2012, 14:22

It is the end of the hose that attaches to the bent (90 degrees) from engine pump. Other end is stock banjo.
What pressure should pump be putting out?
Jeff

68autobug · 03 March 2012, 14:11

Hi jeff
is that the hose that connects to the pipe that comes thru the tinware near the dipstick?
its a pressure hose and fitting. the fitting looks like a JIC hydraulic fitting, although I've never seen one exactly like that..
what happened to the original part? I was thinking it would have been a banjo bolt fitting that they replaced..
I could measure an original part and see if the hole in Yours is the same..
ATF Pump pressure is [can't find My favorite book with that info] couldn't find that info in any other books??
engine oil pressure is about 28psi and its higher than that , maybe 45psi , I'll keep looking for My book...lol

cheers

Lee in Australia

68autobug · 04 March 2012, 01:33

Hi Jeff
the ATF Pressure is 42.5 PSI ..
I found it in one of My albums
not a good pic of the fitting but is that the one?

cheers

LEE in Australia Now in Autumn [Fall] and having a hot summers day?? only had about 10 of these over summer??

Jeff54Griffin · 04 March 2012, 18:45

Yes- the one with the screw clamp on it. I am going to take it off and see what size hole it has.
Jeff

Jeff54Griffin · 04 March 2012, 21:27

I undid the fitting and the hole is small-less than 1/8" with an abstruction at the hose end. Will not let a 3/32" drill through.
What size should this hole be???
Jeff

68autobug · 05 March 2012, 02:30

Hi Jeff
it should be about 7.5mm wide which is larger than 1/4 drill..
if You can get a 1/4" drill in there loosely then that should be OK
Glad You found the problem..
I presume that the ATF should flow at a certain rate all thru the system..
and then have no restrictions on the return... [which are OK]

cheers

LEE in Australia