Author Topic: So you can't figure out why your AAZ is overheating  (Read 13585 times)

May 15, 2008, 09:06:31 pm

jimfoo

  • Veteran

  • Offline
  • ***

  • 2107
    • http://www.66rover.com
So you can't figure out why your AAZ is overheating
« on: May 15, 2008, 09:06:31 pm »
Mine had this problem, running very hot at times. Once it finally died, I converted it to a M-TDI. In the process I had decided to modify the old thermostat and add a second oil cooler(air). My thermostat had a failing rubber seal around the moving part, and when I pulled the rubber off, I found it had a bunch of small holes, which is something I wanted to allow more flow. I also worried about the block off plate maybe not closing the recirc port on the block, or maybe the spring for the plate being too strong. So I took the plate and spring off, put on a much weaker spring and turned the plate around  so it would close sooner, riveting it in place with a washer. The TDI ran much cooler, maybe too cool in winter. So while working on it recently, I decided to buy a new thermostat to get rid of the extra flow.  I got an 87*C. I put it in, and on a short test drive, the temp got up to 230 on a cool day. The radiator was cold. I took it out, put it in a pan along with my old stat and one out of a 1.8 that's in my garage. My old one (87*C also) started opening at 165*F or so, maybe that's why it ran cold, but both of the other ones opened where they are supposed to. I reversed the plate on the new one and replaced the spring, drilled a couple small holes to make filling easier, and put it in. Now it runs fine, temp between 180-190 on normal driving, 200-205 on the hill that I got up to 230 on.
I don't know if the strong spring on the block off plate is too strong, if the thermostats listed for AAZ's are the wrong ones or if the block off plate is just too far from the port, but this mod fixed the problem. So if you can't figure out your overheating problems, try this as it just might help. Also if you are careful and depending on the design, you can bend the brass in on itself to get the block off plate off, then carefully bend it back, heating it first might help keep it from cracking.

Stock on left, thinner spring and reversed plate on right.

Stock on left, rived back on on right. Use an aluminum rivet or brass screw to avoid the rivet rusting off.


Jim
1966 Land-Rover 88" with 1.9 AAZ which has been transformed to an M-TDI
GT1749V, IC , and 2.5" exhaust.
Driven daily

Reply #1July 10, 2008, 07:00:44 pm

stopping

  • Guest
So you can't figure out why your AAZ is overheating
« Reply #1 on: July 10, 2008, 07:00:44 pm »
Are you serious?

This would be a crazy oversight on the part of VW.... I will try it!

I am using an AAZ to push a Vanagon... not over-fuelled but over heating.... new rad... no blockage.... timing is straight not advanced.

I will try it if I can't find some micro combustion gas leaking into the coolant.

Reply #2July 10, 2008, 10:50:33 pm

jimfoo

  • Veteran

  • Offline
  • ***

  • 2107
    • http://www.66rover.com
So you can't figure out why your AAZ is overheating
« Reply #2 on: July 10, 2008, 10:50:33 pm »
When I converted my AAZ to a TDI, then had to replace the head due to me not tightening the IP bracket bolts and the valves hit the pistons and screwed up a lifter, I put a new t stat in. I tested it before and after, and it opened at 190 ish, but the truck would get to 230. I put the old stat, which I had modified, back in, and it brought the temps down to normal. I modified the new t stat and put it in, and I have been fine.
I'm not sure if it has to do with the thinner spring I put on the blockoff disc, or the fact that the disc is closer to the port, but I swear it did fix my overheating problem in both the AAZ and TDI(AAZ block)
Jim
1966 Land-Rover 88" with 1.9 AAZ which has been transformed to an M-TDI
GT1749V, IC , and 2.5" exhaust.
Driven daily

Reply #3July 16, 2008, 05:20:05 pm

zukgod1

  • Veteran

  • Offline
  • ***

  • 2817
So you can't figure out why your AAZ is overheating
« Reply #3 on: July 16, 2008, 05:20:05 pm »
I wonder if this would be the same on our 1.6's?

I have a OE t stat in it now and the plate on the end looks like the one you have with the stiffer spring.
I HAD a lower temp t stat in it that had the lighter spring on it but I swapped it for the OE one as the area where the water passes through on the OE one was quite a bit larger compared to the STANT one I had so I swapped to gain flow.

I've been thinking of going back to the colder one and flipping the plate as you did to see if it helps.
I just don't have the air flow required to keep my car cool while going up hills is my problem but if I can make an improvement in the cooling system I see no reason not to try.
dan

99 Golf TDI (now CNG powered) , 82 TD Caddy

Reply #4October 06, 2009, 03:44:10 pm

wildenbeast

  • Junior

  • Offline
  • **

  • 50
    • The WILDENBEAST
Re: So you can't figure out why your AAZ is overheating
« Reply #4 on: October 06, 2009, 03:44:10 pm »
Has anyone else tried this?  I am also living in the CO Rockies and trying to run cooler oil temps over some of the high passes.  I have a 1.9TD installed in a Vanagon with a high top.

Bill
1990 Syncro Adventurewagen
1.9 Turbo Diesel (AAZ)
http://billwildenberg.shutterfly.com/vwvanagon

Reply #5May 30, 2016, 05:36:39 am

red_method69

  • Newbie

  • Offline
  • *

  • 1
Re: So you can't figure out why your AAZ is overheating
« Reply #5 on: May 30, 2016, 05:36:39 am »
If you have a vanagon and swaped the engine from 1.6 to 1.9, you probably left the original 1.6 exhaust system.
The van is overheating bechause the exhaust is too small. Same problem happened to me 1y engine and 1.6 1990 vw van exhaust

Reply #6May 30, 2016, 12:28:32 pm

theman53

  • Global Moderator
  • Veteran

  • Offline
  • ****

  • 7835
  • Personal Text
    Holmes County Ohio - North Central Ohio
Re: So you can't figure out why your AAZ is overheating
« Reply #6 on: May 30, 2016, 12:28:32 pm »
Jimfoo eventually added another t stat to his upper hose to "fix" the fixed problem. Search it