Transmission Oil Leak

[denny71gt]

The 4 speed transmission in my 71 GT is laying on the garage floor, it is level, I just filled it with oil (to the lower edge of the fill hole) and oil is running out of a hole about an inch below the drive shaft in the front (clutch side) of the transmission. What's happening?

Denny

[guyopel]

When you install the front Bellhousing ( Front Seal and gasket inc. ) the hole is covered and does not leak if you have the Bellhousing installed.HTH
John

[denny71gt]

Thank you for your reply. But it appears that the hole will not be covered by the bellhousing because it lines up with the "recess in clutch housing" (Figure 72-73, Flywheel Housing on Cylinder Block, page 72-38 in the 1971 Opel GT Service Manual). The small hole can be seen in Figure 72-119, Exploded View of 1.9 Engine Transmission (page 72-54, same manual) just above the top of the transmission to clutch housing gasket on the drawing. It would appear that the Main Drive Gear to Clutch Seal Ring would prevent any oil from entering the bellhousing and subsequently the clutch surfaces. But what is its purpose and would plugging it cause a problem?

Denny

[kwilford]

Thank you for your reply. But it appears that the hole will not be covered by the bell-housing because it lines up with the "recess in clutch housing" (Figure 72-73, Flywheel Housing on Cylinder Block, page 72-38 in the 1971 Opel GT Service Manual). The small hole can be seen in Figure 72-119, Exploded View of 1.9 Engine Transmission (page 72-54, same manual) just above the top of the transmission to clutch housing gasket on the drawing. It would appear that the Main Drive Gear to Clutch Seal Ring would prevent any oil from entering the bell-housing and subsequently the clutch surfaces. But what is its purpose and would plugging it cause a problem?

Denny

That's Figure 72-112 not 119.

The front of the transmission is sealed by the gasket (#2 in the referenced Figure) between the transmission against the bell-housing surface, along with the front seal (I believe it is #14 in the same figure) that sits inside the recess in the bell (aka "Clutch") housing, as referenced by #5 but better by #6 in Figure 72-73. The "hole" you describe lines up to the lower part of the recess, but the seal and gasket prevents oil from escaping the recess (and the entire space between the transmission and the bell housing). You can seal that hole all you want, but without both the seal and gasket intact, the oil will instead leak out the main front bearing. The outside of the seal DOES NOT actually seal against the transmission, but against the INSIDE (the "recess") in the bell-housing. The seal DOES seal (when it is sealing ) against the outer surface of the main shaft (#10 in 72-112).

In short, you can't fill the transmission with oil until it is fitted to the bell-housing, with the gasket and front seal in place and all the bolts fixed and torqued. Oh, and the rear seal (#40) and driveshaft as well, not to mention the cover (#49) and gasket (#50) and side shifter seals (two #'s 57)...

HTH

[denny71gt]

You are correct, I was referencing Figure 72-112.

If I understand you correctly, transmission oil can pass through the "little hole" and into the recess, but it can not (or should not) go anywhere because of the gasket and the seal; the oil will just sit in the recess. This doesn't seem right. What then is the purpose of the "little hole?" Why would you want oil in the recess? I must be missing something.

I know one thing for sure, I am going to drain the oil before I attempt to further install the transmission.

Many thanks for trying to help me understand.

Denny

[kwilford]

If I understand you correctly, transmission oil can pass through the "little hole" and into the recess, but it can not (or should not) go anywhere because of the gasket and the seal; the oil will just sit in the recess. This doesn't seem right. What then is the purpose of the "little hole?" Why would you want oil in the recess? I must be missing something.

Exactly. Why did Opel design it that way? Who knows! But one cardinal rule about Opels of that era is to make sure that the front transmission seal, the front gasket, and especially the bolts that attach the transmission to the bell-housing, are up to spec (as in the bolts are properly torqued). If not, then the transmission loses its oil, and then becomes a pile of broken metal shavings. Guess how I know THAT!

[denny71gt]

Many thanks, Keith. I guess this can just be added to the "the great mysteries of life" list.

Denny