D6H transmission overheating

[Pralhad Birdi]

Another thought. After you install the plug use a centre punch to make a couple of dots at the interface between the plug and the valve body to ensure that it can’t move.

Will do. I’ll machine it to interference fit and then do the centre punch on the rim.

 

[Pralhad Birdi]

from what I can remember there should only be the one hole for the orifice I don't remember having to figure where the orifice went. I know that with out it you will have major high pressure. I had a customer that his filter housing blew apart from the pressure

Hopefully this is what’s causing the issue in this case as well, so fingers crossed plugging it sorts out the issue.

 

[Pralhad Birdi]

While you have the control valve body apart I suggest to check closely for a small circular disc of metal with rough edges that will correspond to the missing piece of the plug. It must be somewhere and you don’t want it to get stuck somewhere that could cause chaos to the clutch oil flows. I would hazard a guess that it’s very likely still somewhere in either the valve body or the manifold that fits directly under it when it’s installed on top of the transmission.

I will do. Thanks.

 

[Mobiltech]

I have a d5h valve apart. It has a frost plug in one of the holes.

 

[Mobiltech]

It says 3/8 on the plug.

 

[Nige]

I have a d5h valve apart. It has a frost plug in one of the holes.

Excellent confirmation of what should be in the valve body. Thank you.

 

[Pralhad Birdi]

I have a d5h valve apart. It has a frost plug in one of the holes.

Perfect!! Thank you!

 

[Nige]

Also interesting to note that the frost plug in the valve body shown in the photos posted by Mobiltech appears to be installed the opposite way up to the one that failed in your valve body. In your one the closed end that broke was on the top, in his it is at the bottom where even if the plug cracked like yours did the blank end of it could not possibly have fallen out.

 

[Pralhad Birdi]

Also interesting to note that the frost plug in the valve body shown in the photos posted by Mobiltech appears to be installed the opposite way up to the one that failed in your valve body. In your one the closed end that broke was on the top, in his it is at the bottom where even if the plug cracked like yours did the blank end of it could not possibly have fallen out.

Come to think of it, I’ve never actually seen a frost plug installed the way it was installed on my one, even on an engine block.

 

[Nige]

Come to think of it, I’ve never actually seen a frost plug installed the way it was installed on my one, even on an engine block.

If you are going to manufacture a solid slug to block that port it makes no difference which way it is installed. It just struck me as strange that on your valve block the plug was installed what would be considered as the "wrong way round" compared to the normal way of installation.

 

[Pralhad Birdi]

If you are going to manufacture a solid slug to block that port it makes no difference which way it is installed. It just struck me as strange that on your valve block the plug was installed what would be considered as the "wrong way round" compared to the normal way of installation.

So just a bit of an update:
My local dealer just had one of the part numbers in stock, the 7G-9476 so I ordered that. It’s just been delivered, and it’s not an orifice. It’s a plug with a hole though it (I’m going to attach a photo) and when I Google the part number, both the orifice and this hole come up with the same part number.
The lower hole (the one that should have a frost plug) upon closer inspection actually has this plug with a hole through it.
So I’m not exactly sure what’s going on here.

 

[Pralhad Birdi]

 

[Pralhad Birdi]

 

[Nige]

The part that you bought would still be classed by Cat as an orifice, although it will be completely unlike the other one that you ordered which, when it arrives, will in simple terms be a plastic tube with a small hole in one end and a screen built into the other.

Here are two photos. The one on the left is one of the photos posted by @Mobiltech. The one on the right is from your control valve taken from a post back on Page 2. I've rotated them so that they are both oriented the same way.

The control valve for a D5H is a different Part Number to yours (8P3044 vs 3T5018). It may have the same basic valve body but it is shown in the parts drawing as having a cup (frost) plug Part Number 2A3746 (Ref #21 in the illustration) in the hole directly above the valve spool and no orifice in that area. This is the same as shown by @Mobiltech's photo.

 

[Nige]

Searching through various Part Numbers of D6H transmission control valve that contain the 7G9476 Orifice Plug I came across a better illustration in a control valve used on a 3YG-prefix tractor. In Section G-G it clearly shows the Orifice Plug #30 in the same location as it is in your valve and what appears to me to be an open hole right next to it. How that works I'm sorry I haven't a clue.

 

[Pralhad Birdi]

Searching through various Part Numbers of D6H transmission control valve that contain the 7G9476 Orifice Plug I came across a better illustration in a control valve used on a 3YG-prefix tractor. In Section G-G it clearly shows the Orifice Plug #30 in the same location as it is in your valve and what appears to me to be an open hole right next to it. How that works I'm sorry I haven't a clue.

View attachment 298863View attachment 298864

Thank you for taking the time to look through this.
So do you reckon I should just try to plug that hole and put a plastic orifice in the other one, or does that mean the pressure issues are being caused by something else?

 

[Nige]

So do you reckon I should just try to plug that hole and put a plastic orifice in the other one,

We are getting crossed wires here.....

The plastic orifice with the screen 9W-9830 and its associated O-Ring 5H-8853 (Refs 12 & 19) is installed in a totally different location. See the illustration below. It was on one of your earlier photos taken from the other side of the control valve, white in colour.

The orifice plug 7G-9476 is shown as #34 towards the bottom centre of the illustration.

 

[Nige]

This is what the 9W-9830 orifice looks like inside. In round numbers the hole in the orifice (horizontal on the RH side of Section A-A) is only 1mm in diameter.

 

[Pralhad Birdi]

So does that mean that I leave the control valve as is? No frost plug?

 

[Nige]

So does that mean that I leave the control valve as is? No frost plug?

I would say so. That diagram I posted earlier (Post #75 above) showing Section G-G with the "orifice-plug" in one hole and what appears to be an empty hole right next to it would suggest that is the correct arrangement.

I would be interested to hear what others think.

Have you got the transmission cooler off yet.? What did it look like inside.?