Hi. I realize this topic has been discussed from many different angles in many different threads over the years but I have questions that I did not find answers for so starting a new thread.
I own an '85 FB with about 185k miles. About 16k miles ago, my mechanic at the Mazda dealer I was taking my car to told me the engine had a dowel pin O-ring leak and needed to be rebuilt. She was running great and had no other major issues so I tried using Lucas Stop-Leak for a few oil changes. The leak never went away—but it didn’t get any worse.
An FA owner I met referred me to an independent Mazda rotary mechanic in the area who did a compression test on my engine. He told me that the compression in each rotor (129 and 130 psi) were some of the best he had seen in an original engine with that many miles. Since the leak was not severe, he said it did not warrant an engine rebuilt because the engine compression was still well within service limits, the engine was running good, and the car was my daily driver. He said the engine could run another 50-60k miles the way it was and to stop using any stop-leak products. Instead, he fabricated an oil catch pan under the leak where I place small pieces of Oil-Dri pads and replace when the cloth gets saturated.
All this has happened over the last 3 years. She is still running and driving great. I keep regular maintenance and fix or replace most anything else that is needed. The rate of the leak has stayed pretty consistently low enough that I have had to add little or no engine oil between 3k mile oil changes all these years.
Do I need to be in any hurry to do something about this dowel pin O-ring leak? Does this leak kill the value of my car with it as is? Would anyone buy an FB knowing it has this leak?
Thank you for your feedback.

 

Just keep doing what your doing. Keep an eye on it and if it gets unreasonable, then address a rebuild.

 

welcome to the board.

all i can offer in this case is my opinion, so get your grain of salt.

unless the leak gets so bad as to affect pressure (or require topping the oil off in some ridiculously short interval), just leave it be and continue enjoying the car. a rebuild is the only way to "fix" it.

it's a messy annoyance, yes, and depending on how OCD you are as an individual, it may start working your nerves, but it's not hurting anything. those compression numbers are phenomenal, and as long as you maintain the car/engine, it will be fine. it can obviously dictate when you rebuild, but at this point, we're not there yet. for now, you are in control of that decision.

i can't answer the question about whether or not it will kill the value. i'm sure it's a bargaining tool (and a valid one), but speaking for myself, if i were looking at a car, it wouldn't deter me or break a deal at a fair price.

 

I have a similar leak in my 1980. Same situation as you have in regards to great compression on the original engine. Personally, I just monitor my oil level and clean the engine off ever few drives. Its not a bad leak, just a minor annoyance. I would advise to monitor it and live with it.

 

I remember seeing a thread with a bit of a surgical type of fix for this that involved a small drill bit and injecting an RTV gasket maker. The hole was then capped with a self tapping screw to sort of act as a pipe thread plug.

Seems a bit like surgery where you risk further damage, and if it doesn't work you know have a hole in your housing.

i think future value, the original 12A in good running condition is more valuable. I'd rather buy an FB with this leak then one that had been plugged up with stop leak etc.