Engine is an S4 N/A Mazda Refurb with about 30,000 km in 2 years since it was installed. Car has been sitting since beginning of December for storage but I noticed this leak mid-November when I was replacing the transmission. I don't have anything to remove the flywheel with so that'll have to wait. This engine has also never seen freezing temperatures as it has previously been stored in an underground heated garage during winter months.
Anybody with some thoughts on where this coolant could be coming from?
The pics are from underneath the car looking upwards on the passenger (right) side of the engine.
I don't see any leaks from above the engine - all the hoses to the throttle body are okay.
The coolant around the middle-right freeze-plug is dried, and the only place it's wet is around that tension bolt which you can kinda see in the top picture -but can coolant leak through the tension bolt holes?
Only other thing I can think of is a crack somewhere back there.
I will have to wait and see after I get the flywheel off.


And this is the bottom freezeplug.


This is viewed upward from the driver's (left) side... perfectly fine.


...and you can see the flywheel has been flinging it through the inspection plate so it's all over the place behind the engine. This also suggests it's more than a little 'drip-drip' since it's getting on the flywheel.

 

Leaking freeze plugs maybe. Thats what it looks like to me.

 

Yes, The tension bolts have special seals on the washers to seal the coolant in . before taking flywheel off get a wrench up on that bolt and see if it is loose you might get lucky probably not but worth a try, not to tight they say 28 ft.lbs.should be good . When rebuilt they might have used the old seals some are designed for more than one go . Gerald m.

 

^ okay will try that. Thanks!

 

So this bolt here was the one that was most wet. I could tighten it very slightly with a regular sized 17mm wrench without putting too much force on it - no way to get my torque wrench in there.
I pressure tested the coolant system to about 14-15psi and watched for a couple minutes and I couldn't see any leaks or new drips forming. I was warned not to go above 16psi or I might blow an internal coolant seal.
Solved? Thoughts?

 

Scratch that, I'm going to pull the flywheel and fix this properly by replacing the seals.

 

Pardon the n00b question but...
Are you supposed to be reefing on the bolt head to tighten it?
I always thought you tightened from the nut end of the assembly, not the head end.
Seems like cranking on the head would be a good way to snap the bolt rather than tighten it.

 

While you're back there, replace the freeze plugs as well. It couldn't hurt to give yourself some cheap insurance, right? I like to use aircraft form-a-gasket on the sides of the freeze plugs to ensure a good seal. Just knock them out with a punch and hammer, then get a socket that fits just inside the cup and give it a good whack. Buy a few extras in case you screw up. Also, replace the tension bolt seals one at a time. I don't think I should have to say that, but you never know what some people might do.

 

What nut? They're just long *** bolts.

 

Happy to hear that tightening them did the job even happier to hear that you are going to fix proper . I thought the tranny and all was still hooked up. Might be a good idea since you can't clean the threads in the iron to put a little never seize on the bolt threads just so they torque a little easier . Dirty threads make a torque wrench lie big time , a little down the road you could end up with the same as what you have now . Good luck Gerald m.

I'll bet a cookie that the bolts are all a tad loose .

 

Start at 37:30 of Aaron Cake's video:
Part 12: 13B Rotary Engine Rebuild - My 76 Mazda RX-5 Cosmo Restoration - YouTube

I wasn't "reefing" with a ton of force on them since I know they only require 28 ft-lbs and I was only using a wrench - and had no way of telling how much I was tightening.

 

and AGreen I don't really want to bother with the freezeplugs if they aren't leaking... I know they don't normally get replaced during rebuilds unless something is wrong with them. lol One at a time should be a given...

 

if the bolt was loose, then that is probably the problem, i would check all of them, since you're there. if you change the bolt seals, do it one bolt at a time.

20-25psi is perfectly safe for the cooling system, you actually do want to give it more pressure than normal to find any leaks

 

Do one bolt at a time of course. the seals are cheap.

 

Just wanted to update this thread here... I finally put in the order for the seals along with a bunch of suspension stuff so I started replacing tonight. Only got through a couple before my *** froze to the cement in my garage.


I've been updating my project thread since it's come in for winter storage if anyone wants to check it out!
https://www.rx7club.com/canadian-for...thread-959424/

Thanks for all the replies gents.

 

sometimes it's best to not do any repairs before the pressure test, it may give more confidence in what the root cause was so that it could be repaired. sometimes leaks only show on hot engines versus cold.

for the future.

 

^ agreed. I did the pressure test again up to 20 psi and it continued sweating/dripping from the two right-most seals. Hence the replacements. Just because they were cheap, I ordered the freeze plugs but I don't want to touch them yet since they didn't show signs of leaking.
I haven't tested for leaks with the engine hot but I suppose it could be coming from a freeze plug while the engine is at op. temp?

 

most likely a faulty freeze plug will have corrosion pinholes on them where the rust is working it's way through the metal. if they are totally shiny then they are unlikely the cause.

so clean them off and thoroughly inspect them, even if you have to poke suspect areas with a pick or awl. you won't damage a good freeze plug, but a bad one will start gushing as soon as you find a rotten spot.

 

Think this might me the cause of the leak? I don't know if this could have happened while unbolting/taking it out but this is from one of the leaking bolts.

 

not likely, the tension washers almost always rip like that when removing them.

 

darn