Just wondering if anybody knows the exact sizes (length and dia) of an original hydraulic oil surge tank that bolts on top of the hood of a d4 7u as I am going to have to make one. Any help would be appreciated thanks.

There were several styles, this is one of them (late).
I'll take dimensions and post later today:D

Of all the 100s of D4s I worked on & around I never saw one with a surge tank like that on the hood. Was it a special application that it was used for or what? The only tank up in that area was the HT4 loader that I ever saw but was a pretty big long rectangular tank on top the engine. Just wondering.

Tank dimensions are approx. 25 inches long, 8 inch dia.

SJ,
They really weren't all that common, they were part of the two-valve, four pipe #44 system and used with the #40 scraper to help cope with the large volume of hydraulic fluid movement.

OM I kind of thought it was a special application of some type like that & thanks for the reply.

Hello OM, Is that an early series tank or a late series one which you posted a pic of? A relative has D4/7U#15195(1951) with a similar tank. The only difference is that there is no nuts and bolts on either end of the tank. The tractor was purchased with the tank and all the plumbing used in 1955. Still runs like a top. Also has a caterpillar 4A blade on it. Electric start pony and lights.

I guess the answer is both....7F4855 Hydraulic Air Tank Group Second type (with hood reinforcement mounting plate)(eight bolt tank and plate mounting and another six bolt plate mounting is shown as application for 7U1-up, 2T1-9999 and 5T1-5T7411. I show five different combinations involving three different groups, all of which would interchange so they probably grabbed what they had.
I kinda like the idea of having a clean out but I have never been in there:)

Thanks guys for your help, I didnt realise there were so many different types anyway thanks again for your help. Will post some pictures of the finished tractor and 40 scraper WORKING hopefully!