I'm going to rebuild the engine.
Upon draining the coolant I noticed oil droplets, also brown sludge in the overflow tank.

As I'm taking the engine apart, are there any places I should be looking for where oil and mix with the coolant?

Never rebuilt a 12a before so I welcome any and all suggestions.

thanks.

 

Not sure if the 84 gsl was one of the ones that came with the beehive cooler but if there is a rupture on the internals of that it could be there. The beehive was used as the oil cooler on a few of the 12a engines from 83-85 and you will know it if you see it by looking just below your oil filter and if there is a giant mass of metal that looks kinda like a beehive then you have it.

Outside of the beehive I can't think of anyway for oil to get into your coolant. Internally to the engine if there was a leak into the coolant jackets then you would get fuel in there first, plus you'd notice the power is dropping plus your coolant levels dropping off.

 

^+1 on beehive cooler. If you can locate the parts, a good reliability mod is to junk the beehive and install the fmic from an earlier year. You will have to change the radiator to the shorter style and may have to add a bracket or two, but it will cool the oil better and prevent this from happenning in the future. And it makes the engine bay look a little cleaner without that bulky p.o.s. "cooler" on the side of the block.

 

basically except for a freeze plug on the front iron under the front cover its not possible for a rotary to mix oil and water. its really rare for this to fail and its usually a huge leak.

some gunk in the coolant is pretty normal, its not oil. and some gunk on the dipstick is normal, its not coolant, just condensation.

 

No leaking on the beehive oil cooler. All dry except for some user spillage.

Because I was catching the coolant in cat liter pans when removing the radiator hoses (2 days ago) and did not get around to transferring the contents to other containers, I think the floating drops of oil were just that, oil dropping off the engine and adjacent parts.

Thanks for the "some gunk in the coolant is pretty normal." What I poured out of the overflow bottle would lead me to believe that bottle has never been cleaned out. Real nasty looking like runny pudding at the bottom.

Distributor and rats nest are next on the list to come off.

Truly I would not be attempting this if this site/community did not exist.

 

No. 1 rebuild recommendation:
-buy Mazdatrix 13b rebuild DVD. Priceless info (99% applies to 12a).

Been there. Best $30 I spent.

Stu Aull
80GS
Alaska

 

Yup. Got the Atkins one first, then the Mazdatrix one, which has much more detail and really useful suggestions in terms of knowing/tracking where every part came from so they all go back in the same place.

Thanks.