[C2] 1967 big block rear main seal
07-26-2021, 12:10 AM
#1
1967 big block rear main seal
I am sure this thread has been answered before but need to ask the question and appreciate any expert advice in advance.
We own a 1967 BB coupe with the 427 chev. We have a oil leak between the bel housing and gear box. 99% it is the rear main seal. Now this seal from what I understand is a 2 piece seal, can it be accessed by just removing the gearbox and bell housing?? Any advice would be greatly appreciated from Melbourne Australia.
We own a 1967 BB coupe with the 427 chev. We have a oil leak between the bel housing and gear box. 99% it is the rear main seal. Now this seal from what I understand is a 2 piece seal, can it be accessed by just removing the gearbox and bell housing?? Any advice would be greatly appreciated from Melbourne Australia.
07-26-2021, 12:35 AM
#2
Drifting
Seal
Short answer is no. Do not remove the gear box (transmission). You need to remove the oil pan and rear main cap of crankshaft. There are lots of videos on internet how to change this seal.
07-26-2021, 12:39 AM
#3
Drifting
Big block
I have not done it on a big block, but on a 327 you need to lower the steering from idler arm to clear and remove oil pan. You may need to loosen other main caps of block to move the crankshaft enough to slide the seal around.
07-26-2021, 06:13 AM
#4
Racer
Try Blue Devil Rear Main Seal stop leak first, you will be amazed.
SWC Tim
SWC Tim
07-26-2021, 07:29 AM
#5
Race Director
Replacement on a BB is same as for a SB in a Corvette. Unbolt the idler arm and toe in the front tires to pull the drag link assembly down to clear the oil pan for removal. If it hangs up on the front crank throw, rotate the engine 180 degrees to get clearance. I didn’t loosen the other main caps when I replaced mine. Might be a good idea. The seal slid in on mine without much problem. Be sure to follow the instructions closely for positioning the seal ends, spot applications of RTV and since the rear bearing is the thrust bearing, pry the crank forward and then back to check clearance as you re-torque the rear main.
07-26-2021, 08:46 AM
#7
Le Mans Master
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"We have a oil leak between the bel housing and gear box. 99% it is the rear main seal."
Generally a rear main seal will leak at the back of the oil pan / front of the bellhousing down the dust shield, but may be blown to the rear of the car when driving.
Have you checked the oil in the gearbox? The Muncie has a history of countershaft / case leaks that would be at the intersection of the gearbox and bellhousing. If the back of the oil pan / front of the bellhousing (dust shield) is not covered with oil, that may be your problem.
I check the oil in the transmission although a small leak create a big leak. Clean up both areas well, and run the engine to monitor for the leak before ripping it apart.
Generally a rear main seal will leak at the back of the oil pan / front of the bellhousing down the dust shield, but may be blown to the rear of the car when driving.
Have you checked the oil in the gearbox? The Muncie has a history of countershaft / case leaks that would be at the intersection of the gearbox and bellhousing. If the back of the oil pan / front of the bellhousing (dust shield) is not covered with oil, that may be your problem.
I check the oil in the transmission although a small leak create a big leak. Clean up both areas well, and run the engine to monitor for the leak before ripping it apart.