[dataway]

I'd have to pull the trans back off the engine to do that.

I know the back half is original ... the front half replaced around 1980. So your guess is as good as mine. I can't remember if I replaced it, or the local Bubba style transmission shop replaced it.

The whine is intermittent, and pretty much non-existent when the trans is up to temp. Which leads me to believe it is centered on the suction side.

Although warm fluid would also effect the pressure relief.

Basically what happens next is I drop the pan and replace the filter, check for "debri", install a filter with screen, check the o-rings ... if it still whines, it comes off the engine and I'll pull the pump and at that point I'll have some casting numbers for you.

[242177P]

The one on the right says 895. (it's between 11 and 12 o'clock)

[dataway]

Jeez, good catch .... and I just realized I've been looking for that Nikon lens cap for about two months

So I have an 895 front ... makes sense because the pump was replaced in the late 70's. Pretty sure the pump back (half with the shaft) is original to the 68 trans ... can't think of any reason I would have ever changed that.

So ... I've most likely got a 121 back, and a 895 front .... are they compatible arranged in that way?

I notice the pump back has a 32 cast in it.

[Half-Inch Stud]

Originally Posted by dataway

Jeez, good catch ....So ... I've most likely got a 121 back, and a 895 front .... are they compatible arranged in that way?

I notice the pump back has a 32 cast in it.

Ahem, eh uhm thatsa the worst possible pump half incompatability (my opinion). My memory indicates the 121 & 895 COVERS do not share the same back cover. as if the 121 backside will whine on an 895. but the 895 backside (an 896) may be fine with the 121 COVER. After building a whiner TH400 30 years ago, Ive made a point to never mix these pump halves.

However the attached chart seems to say it all good with the 895 COVER. Im away from my original files, so I cannot VETT the attached chart with my chart. Attached chart say you're fine.

CKperformance provides a thorough TH400 Front-Pump review; GM-referenced and shop "blueprintint"

http://www.ckperformance.com/images/...ut/OILPUMP.pdf

[dataway]

HIS, thank you for the info, very thorough. And I downloaded it for reference.

Unfortunately it looks like I'm not going to be able to get a pump cover number without pulling the trans back apart. But I can see from my photo records that my pump cover does have the hole for the regulator so it is an early model ... probably 121.

A little confusing which is the body and and which is the cover ... so the section with the gears is the pump body and the section that goes farther inside the trans is the cover? Seems backwards.

Jeez, who knew it was so complicated ... I thought at TH400 was a TH400

[Half-Inch Stud]

My official Chart is clear, whereas THAT chart looks official yet has the name "Cover" indicating the Backpart, so hmmmmm.

If those "NO" row/columns represent Switch-Pitch covers/backs then i call BS because anybody would know this sort. Im away from me TH400 Build book (a personal set of instructions) that contains the Chart.

Seems you could keep goingand pull the TH400 at a later date despite your firm opinion that you cannot. Ive been able to R&R TH400s from pristine Pontiacs with no harm, and only improved on the owner's car condition...in same day, using hand tools.

[Cliff R]

It's not really that complicated and you will find that any transmission that had a decent lifespan will have underwent changes and upgrades over the years of production. Some were done to make them more reliable and function better. However some were done to save production costs, like the use of plastic parts instead of metal.

For oil pumps in particular I am NOT or ever have been fond of mixing and matching halves or even using an early pump on a later trans or visa-versa.

The oil pump as mentioned earlier has never been a problem area for the TH400 as they are very well made and in almost all cases when you find a decent core the pump will be fine and well within spec. A quick visual inspection of the parts once you get it apart will tell the story. Most I've seen that are damaged were the result of someone putting the inner gear in the wrong direction and the torque converter bottoms out and destroys the gears and pump halves.

There still seems to be a decent supply of hard parts being offered for the TH400 although good cores are getting a little harder to find since it's been quite a while since they went out of production. I still have about 40 cores here and used to pick them up for next to nothing, thinking I'd use them for hard parts at some point. In all the years building these transmissions I only dove into a few of them to get hard parts and most of those were gutted to get the early smooth direct drums for the 34 element sprag upgrade. Once the 4L80E drums became readily available, I started using those instead and quit taking my good cores apart looking for the good drums.

The 4L80E direct drum is a nice upgrade and I also use the molded apply piston and high-energy frictions in them, plus the 34 element sprag and spiral lock ring to hold the retainer in place. That's a rock-solid set-up when building a TH400 and those part are still readily available........Cliff

[dataway]

So ... if in fact I do have to change the pump .... I'd be looking for a 121 front pump section to match my 121 rear pump section?

I'm going to double check my dip stick length also .... to make sure I'm not making any mistakes in fluid level .... were the 2 speed and TH350 tubes/sticks different enough that I would have noticed it compared to TH400 pieces?

A quick search looks like 121 pumps are getting kind of rare. I'm seeing a few used examples. Also quite a few places listing the 895 as suitable for 64 and up TH400s.

Noticed in my pics that my stator (rear pump section) has eight bolt holes and the 895 front half has six.

[Half-Inch Stud]

121 are the most desired. Always 8-bolt.
895 are 8,6,5 bolt covers as time cheapened production

[dataway]

Looks like I can pick up a 121 on ebay if necessary.

Might just make it happen .... the car has been apart for 40 years ... why worry about a couple of hours to change out the pump.

[Cliff R]

I have bins full of pumps and other TH400 parts, haven't looked at them in at least 10 years but probably have half a dozen good pumps in there that have never been apart......Cliff

[dataway]

Originally Posted by Cliff R

I have bins full of pumps and other TH400 parts, haven't looked at them in at least 10 years but probably have half a dozen good pumps in there that have never been apart......Cliff

Time permitting ... when you get a chance, give me a quote on one if you can. I trust you more than ebay

[Cliff R]

I didn't get a chance to look today, will take a look tomorrow to see what I've got and let you know.....

[dataway]

Tonight I pulled the pan and double oringed the pickup tube, and installed a bronze screen type filter.

Fluid color etc. was good, there was a bit of metal in the filter, nothing in the pan, nothing that appeared to be a pattern of similar particles, just a few pin head size pieces ... I did accidentally abuse the parking sprag a couple of times while testing it lately.

Tomorrow I'll fire it up again and see if it sounds any different.

[dataway]

So today I start the engine back up on the stand ... not a sound, trans is absolutely quiet. Goes through all the gears, everything seems perfect.

So ... suction tube oring was leaking? Felt type filter too restrictive?

I'm using Valvoline synthetic fluid ... it seems a bit thick compared to old school trans fluid. Wonder if the added resistance to flow when cold makes the trans more pron to sucking air or not getting enough fluid when cold. During my previous tests before double oringing the suction tube and changing to a screen filter the whining would slowly go away as the trans heated up.

So thanks to everyone for the help.

Cliff, if you happen on a 121 pump, 121 gear-half in your usual parts sorting, I'd still be interested in it as a spare, no hurry at this point.

[Cliff R]

I'm headed out to look here in a few, been buried in other things today and haven't had an opportunity to check yet.....