Topic: thermostat question

[yota_krawler]

I have an 85 22r and I am just wondering how your truck would run if the thermostat was bad? Thanks Cody

[highridin4x4]

If its stuck closed it would run hot. If it was stuck open it would run cold.

Scott

[yota_krawler [OP]]

I am asking becuse when my truck is cold it runs pretty good but once it warms up it boggs and runs really shitty when you are just barly in the gas but if you are into the gas pretty good then it runs great. (if it makes sence)

[jimbo74]

sounds more liek a tuning issue

how is the cold idle setting and the AAP?

[yota_krawler [OP]]

what?

[Blingn]

Some 1985 carbureted, federal emissions specification trucks may exhibit a slight hesitation when accelerating from a stop, or during light throttle acceleration at low speeds.

CAUSE:

This condition may be caused by:

(1) Lean air fuel mixture.
(2) EGR influence on lean mixture.
 

CORRECTION:

(1) Operating temperature of the EGR valve BVSV has been changed from 40~C to

60~C.
 
(2) Diameter of the slow jet has increased from 0.50mm to 0.52mm.
 
(3) Diameter of the main jet has increased from 1.14mm to 1.17mm (ATM) or 1.16mm (MTM).
 
(4) On high altitude specification vehicles, the carburetor air horn has also been changed to allow installation of the new jets.
 

PRODUCTION EFFECTIVE:

From Engine Number                             Production Date

     22R-1590303                               September, 1985
PART NUMBER INFORMATION:

The following part numbers have changed in production as of September 1985.

Previous Part Number                   New Part Number                         Part Name

      21100-35290                           21100-35291                Carburetor Assy (MTM)
      21100-35301                           21100-35302                Carburetor Assy (ATM)
      25820-13010                           25820-13020                Valve Assy Bimetal

SERVICE REPLACEMENT PART NUMBER INFORMATION:

To correct a hesitation condition on vehicles produced prior to September 1985 the following parts must be replaced as a set.

      Part Number                     Part Name

      21205-35210                     Jet, sub assy, slow (ATM & MTM)
      90999-41116                     Jet, first main (MTM)
      90999-41117                     Jet, first main (ATM)
      25820-13020                     Valve assy bimetal, (ATM & MTM)

On high altitude specification vehicles the air horn must also be replaced.

      Part Number                      Part Name

      21112-35291                      Horn, air (MTM, high altitude)
      21112-35300                      Horn, air (ATM, high altitude)

[yota_krawler [OP]]

wow thanks but it doesnt sound like an easy fix, I got all the stuff for an efi swap and was just hoping i could get it running better before the swap but might as well just deal with it until i swap it but thanks blingn!

[toyotanner]

you can always take the thermostat out and it will always run cold 

[93tonkatoy]

If you remove the thermostat, make sure you watch your temp gauge. If you build up heat quickly, for any reason (going uphill, hard acceleration, towing a trailer) the coolant may run through the radiator too quickly to get cooled, and may actually overheat. If you have an old thermostat, pull the guts out of it and install the ring. This will put a restriction in the flow to slow the water speed thru the radiator.

[fordh8r]

  The problem may not be the T/stat. Although, changing it isn't expensive or difficult for just the sake of trying to remedy your issue.  Do not omit or modify the T/stat as it will cause unwanted cooling properties such as taking too long to warm up (sucks in winter time, no heater) and once it does reach operating temp it will have the tendency to overheat from excessive coolant speed through the radiatior by not being regulated by the size of the opening of the T/stat (omitted or modified).  It will also cause uneven cooling of the engine as well which is not conducive to keeping it from wanting to blow a head gasket as well.  We all know how these 22R's already don't need any help here. 

  In fact the BSV, which controls the EGR vac circuit, basically has a T/stat built into it and operates via the coolant temp (near the T/stat housing). So it operates independently of the T/stat anyway. Which is why there was the changes made as noted in the info that BLINGN posted.

(1) Lean air fuel mixture.
(2) EGR influence on lean mixture.
 

CORRECTION:

(1) Operating temperature of the EGR valve BVSV has been changed from 40~C to

60~C.

  I'm not saying that this is in fact the solution to the problem you're having. Just consider it strongly as a possibility since what is in this info is a step in the right direction of things to consider. Along with the other info offered in this section as well. That's all.   

  Other things to check as well, start with basics such as timing advance. Check for bad vac advance or sticking mechanical advance on the dist. and look to see if you don't have a bad accelerator pump or anything like that.  Also does it need to be tuned up? Always start with the simple stuff and go from there.  Hope this helps. Good luck fixing your rig!    Keep us posted with what you find. 

[yota_krawler [OP]]

I will thanks for all the info, hope i can figure it our soon!

[86bobbedtoy]

Its a typical toyota carb issue,
Do the efi swap and save yourself the headache

[yota_krawler [OP]]

thats what I am planing on doing, but efi swap aint no walk in the park either!