View Full Version : TR6 TR6 Oiler Filler Cap

10-08-2004, 08:34 PM
Anyone know whether the oil filler cap on a 73 TR6 is vented. Mine has a small hole in the center that goes all the way thru. IF I plug it the engine seems to run better. Was the TR6 a presurized oil lube system. Thanks in advance for all answers.


10-08-2004, 09:04 PM
Jerry, you can open a whole bucket of worns with this question. Sounds like someone has removed a few emission control peices and vented the value cover by putting a hole in the oil cap. Do you get alot of leakage around the cap when you drive? Wayne

Geo Hahn
10-09-2004, 12:11 AM
I think they stopped venting to the atmosphere early in the TR4 run... since then TR's (US spec at least) oil filler caps are sealed. There are several causes of excessive pressure within the valve cover including (as noted) modification of the original emissions equipment.

Wouldn't expect the presence or absence of a small hole here would have a noticable effect on engine performance but then I haven't tried it. Is there a nice film of oil on the underside of the bonnet?

10-09-2004, 08:15 PM
Geo, you and I are on the same track and we both know how someone can screw an engine up by blocking everything up. We both got the same vision of what it looked like under the hood. With the engine running better with the hole blocked do you think it's possible that the carbs are loosing that much vacuum with that hole open and when he blocks it off they operate correctly or better anyway. Wayne

Dave Russell
10-09-2004, 11:45 PM
Hi Jerry,
I think the hole should be blocked.
Here is a good reference: https://www.mgbmga.com/tech/mgb9.htm
Although it is for a MGB, I suspect that the Triumph is similar. See the section on "Carb Control System, 1969 & onwards.