Specifications of thermostat for 4AFE

[Noodles2302]

I need to replace the thermostat in a 4AFE and am wondering what the correct specifications/dimensions for these are.  My local Toyota dealer does not have any in stock at the moment.  Checking aftermarket options to suit the 4AFE, I see different physical specifications between different manufacturers.  Some have 29mm foot size, whilst others have 27.7mm foot size.  Variations in foot-to-flange height also exist in these aftermarkets ones, some 35mm, others 34mm.

Does anyone have knowledge on what the correct dimensions are for the thermostat as if I am forced to go with an aftermarket one, I want to make sure that I am getting one that is the right specification?

[Tony Prodigy]

Don't let all those numbers confuse you. All you need to look for is the manufacturer recommendation. If it's designed to fit the 4AFE engine, then it will fit regardless.

Here's a few to get you going. Both high quality aftermarket.

Dayco Brand

Gates

 

Edited February 2, 2021 by Tony Prodigy

[Hiro]

There could be variations between a Gen1 4AFE (AE92) and the Gen2 (AE101) which might account for different dimensions/part numbers in catalogues.

[Tony Prodigy]

10 minutes ago, Hiro said:

There could be variations between a Gen1 4AFE (AE92) and the Gen2 (AE101) which might account for different dimensions/part numbers in catalogues.

Yeah, more than likely the two might have different temperature ratings which would dictate the stem depth/height but the overall neck sizes should be the same.

[Hiro]

Yeah, more than likely the two might have different temperature ratings which would dictate the stem depth/height but the overall neck sizes should be the same.

There are significant differences in head design between the two generations, so wouldn't be out of the ordinary for it to be a physically different size

 

Sent from my SM-G970F using Tapatalk

 

 

 

[Tony Prodigy]

2 minutes ago, Hiro said:

There are significant differences in head design between the two generations, so wouldn't be out of the ordinary for it to be a physically different size

 

Sent from my SM-G970F using Tapatalk

 

 

 

Probably best if the O.P enquires with his specific build date to ensure correct fitment. You wouldn't think something as simple as a thermostat could differ from one gen of the same engine to another. Would be nice to see pictures to be able to compare.

[Noodles2302]

The car in question is a 1994 build.

Am also wondering if it is possible to replace the 2 studs that locates the thermostat housing and the retaining nuts screw on to.  Have seen some diagrams that indicate these are separate parts to the water inlet housing.  Or does that require special tools and it is easier to just replace the entire water inlet housing?

[Tony Prodigy]

8 hours ago, Noodles2302 said:

Am also wondering if it is possible to replace the 2 studs

The studs are removable. Just use a pair of vice grips and gently unscrew them. Anticlockwise rotation. There may be thread lock on the threads, but they should rotate.

Vice Grips.webp

[Noodles2302]

Many thanks Tony.  Vice grips to the rescue.

[Hiro]

Other way to remove studs is to thread two nuts on there and then try and unscrew the inner nut, gets more purchase than a pair of vice grips and less likely to strip the thread (although you need to have enough thread sticking out for it to work)

[Tony Prodigy]

Usually the threaded section at the bottom of the stud is not used which is why I suggested the vice grips. I wouldn't attack the working part of the thread. It's common sense right ? The two nuts will work a charm too, of course.

[Noodles2302]

Studs removed.  Vice grips did the job.  No evidence of thread lock, but they still needed the vice grips to get them moving.  Now just trying to locate replacements.

[Noodles2302]

Replacements are proving hard to find.  Nothing in stock in the whole land for genuine ones.

Wondering if they are just mild steel studs and a generic of the right diameter, length and thread pitch would suffice?  Will do some measuring tomorrow.

Last resort will be to find a wreck and strip them out.  Not my first choice, But at least I am well practiced at removing them.  If I have to go  down this route, it won't be with vice grips.  It will be with a proper stud extractor or the two nut technique.

[Hiro]

Tried Amayama?

[Noodles2302]

Thanks for suggesting.

8 weeks delivery time ex-Japan. 

Will continue to search.

[SRA]

When it comes to things like thermostats my recommendation is to stick to the original, even if you had to buy an aftermarket one to keep the car running that should only be temporarily until you get the original. I believe the Toyota dealer should be able order it for you even if it took sometime to arrive, it won't be longer than other suppliers anyway.

[Noodles2302]

I have installed an aftermarket thermostat for now.  Was able to source some M6 * 30 mild steel studs to replace the existing studs.  All installed, new coolant added, burped to ensure no air pockets and road tested under a wide range of driving conditions (freeway, stop start traffic jams, suburban driving).  So far so good.  Temperature rock solid, indicating just under half way on the temperature gauge whereas before it hardly moved off Cold.  Thanks for all of your help.

I do have OE studs on order from a Toyota dealer so might end up putting those in if they ever arrive.