Overheated on track - now what?

[vex]

Originally Posted by infernosg

Both valid points. What seems to be missing though is any sign of an external leak. I'm not seeing anything from any of the lines; nothing from the radiator and nothing coming out of the "weep hole" on the water pump housing. By "signs" I mean no leaking fluid, no evidence of dried fluid, no steam while running, no coolant smell, etc. Also, if there were a small leak allowing air into the system wouldn't that air just bleed off and stop at some point? The system is pressurized when the car is running so wouldn't that prevent additional air from entering?

No. There is no check valve in a pinhole leak if it's present. If water gets out when at pressure, air will come in when there isn't. It's basic buoyancy and pressure differentials. The system will suck in air wherever possible as it's less dense and requires less energy to reach equilibrium pressure.

I'm not sure if I'd say the pressure test "passed". I brought the system up to 15 psi and within 10-20 minutes it had dropped to 14 psi. You would think a perfect system would hold pressure indefinitely.

I still think I'm missing something about the bubbling in the overflow bottle. Something is causing a pressure build-up in excess of 0.9 bar but it's not a constant stream of fluid that's coming out like what would happen with an over-filled system. It's a mostly steady stream of gas, whether it be escaping air pockets (but they never stop), boiled fluid (possibly a result of a stuck thermostat) or exhaust gases I'm not sure. I suppose the only way to tell is to have the system checked for the presence of exhaust hydrocarbons but I don't know where I'd go for that.

Coolant rarely ever is a constant stream coming out. You'll have some gas, but this is usually just gaseous coolant vapor. If however the system has air when it's coming back in from the reserve tank you have issues.

I have a new thermostat that is not yet installed and a new radiator, water pump and full set of hoses on the way. Is there any hope that installing all those would rectify the issue? If not, I guess I'm just going to have to tear the engine apart.

No. What you might be able to do to confirm where your issue is; would be to break the coolant system into sections. Separate the radiator from the engine section and test each section. For instance you can block off one outlet on the water pump and pressurize the other. Check pressure after a few hours. Do the same for the radiator and you'll know which one's holding pressure and which one is not.

If your radiator isn't holding pressure because the brazing is falling apart that might be your issue, but if you haven't noticed leaks with it.... then well... That's what I'd do at least.

[infernosg]

Originally Posted by vex

No. There is no check valve in a pinhole leak if it's present. If water gets out when at pressure, air will come in when there isn't. It's basic buoyancy and pressure differentials. The system will suck in air wherever possible as it's less dense and requires less energy to reach equilibrium pressure.

You forget you're talking to another engineer here (and a VT AOE graduate to boot), but that is what I was getting at. If air entered through some small tear with the car off (under vacuum) it would be pushed out with the car on. The air would be pushed through the path of least resistance - the open radiator cap. However, because the car is on no additional air can enter so at some point the bubbling would stop. What I have is a constant stream (continues for more than 10 minutes) so this leads me to believe it is not the issue.

Originally Posted by vex

No. What you might be able to do to confirm where your issue is; would be to break the coolant system into sections. Separate the radiator from the engine section and test each section. For instance you can block off one outlet on the water pump and pressurize the other. Check pressure after a few hours. Do the same for the radiator and you'll know which one's holding pressure and which one is not.

If your radiator isn't holding pressure because the brazing is falling apart that might be your issue, but if you haven't noticed leaks with it.... then well... That's what I'd do at least.

I'd love to pressure test every component but I just don't have the means.

I'm inclined to believe ReTed that there is a small failure point likely on the compression side of the rotor housing. This would explain why I don't have a continuous cloud of white smoke because the pressure is keeping the coolant out, but would explain the little bit I get after starting the car after it's sat for a while. It's always done that but I just assumed it was condensation. I can think of nothing else that would cause the continuous build up of pressure. I guess the HPDE just pushed it over the edge. I was really hoping the stock engine would last more than 105k miles...

[vex]

Originally Posted by infernosg

You forget you're talking to another engineer here (and a VT AOE graduate to boot), but that is what I was getting at. If air entered through some small tear with the car off (under vacuum) it would be pushed out with the car on. The air would be pushed through the path of least resistance - the open radiator cap. However, because the car is on no additional air can enter so at some point the bubbling would stop. What I have is a constant stream (continues for more than 10 minutes) so this leads me to believe it is not the issue.

It was more for other individuals reading than for you . Do the bubbles correlate to the heat increase? Or is it independent? IE if you run the engine; reach operating temperature; bubbles stop or bubbles continue but operating temperature is maintained.

I'd love to pressure test every component but I just don't have the means.

And you call yourself an engineer . Hit up Lowes/Home Depot and build your own for less than $50.00.

I'm inclined to believe ReTed that there is a small failure point likely on the compression side of the rotor housing. This would explain why I don't have a continuous cloud of white smoke because the pressure is keeping the coolant out, but would explain the little bit I get after starting the car after it's sat for a while. It's always done that but I just assumed it was condensation. I can think of nothing else that would cause the continuous build up of pressure. I guess the HPDE just pushed it over the edge. I was really hoping the stock engine would last more than 105k miles...

If it's how I imagine it is working than that small failure point is an indication of the casting failing... which 'shouldn't' happen on an S5.

[infernosg]

So I went out and fiddled with things again; this time I took some video. I don't know how to embed these so direct links will have to suffice.

First, here's the behavior when cold:
https://picasaweb.google.com/lh/phot...eat=directlink

Next, fully warmed up:
https://picasaweb.google.com/lh/phot...eat=directlink

Last, here's after revving the piss out of the engine. Notice the coolant level:
https://picasaweb.google.com/lh/phot...eat=directlink

Just for giggles, I think I may have found an exhaust leak. Yes, I know I should not be revving the engine like this:
https://picasaweb.google.com/lh/phot...eat=directlink

[vex]

I don't know... It really seems like a fire ring has decided to let go.

[infernosg]

Originally Posted by vex

I don't know... It really seems like a fire ring has decided to let go.

Yeah, it wasn't too happy starting this morning. Basically, I've already started looking for engine stands, hoists and other tools needed to pull the engine. Likely going to start the teardown this weekend.

[Pete_89T2]

Ouch, after looking at the videos, I have to agree it looks like a teardown is needed.

[tweiss3]

I wish i had time this weekend to come down, I have an engine hoist i could bring with me.

[infernosg]

Well any doubts the engine is fried have now been eliminated. Started the car after work and even though it started right up it sounded like it was only running on one rotor. Eventually the engine caught itself and I was able to drive home. Got home, shut it down and changed, came out to start it to depressurize the fuel system and it absolutely would not start. It took me 30 minutes to start it again and the same thing happened - started on one rotor but after a few revs and about 30 seconds the second rotor kicked in. Pulled the fuel pump connection and let it stall out and started the teardown. Can't wait to see what exactly happened.

[vex]

Originally Posted by infernosg

Well any doubts the engine is fried have now been eliminated. Started the car after work and even though it started right up it sounded like it was only running on one rotor. Eventually the engine caught itself and I was able to drive home. Got home, shut it down and changed, came out to start it to depressurize the fuel system and it absolutely would not start. It took me 30 minutes to start it again and the same thing happened - started on one cylinder but after a few revs and about 30 seconds the second rotor kicked in. Pulled the fuel pump connection and let it stall out and started the teardown. Can't wait to see what exactly happened.

This doesn't make sense...

[infernosg]

Originally Posted by vex

That looks about normal for a long life engine. Maybe you should clean it more often

How does an engine coked in oil look normal?! 105k miles is also hardly what I consider a "long life engine". Hell, I've only put 5k miles on it in nearly two years of ownership. This also isn't a show car. As long as it (was) running I didn't really care how clean it was inside or out.

Originally Posted by vex

That is an easy fix. Mine did the same thing until I broke it loose. Use some penetrating oil (pb blaster and the like) on the internal chamber (you'll need to spray it into the hole) and on the shaft, let it soak in over night. Then chuck the actuator in a vice or secure it to a wood block and push the shaft to break any of the other debris. Flush with more penetrating oil. Once cleaned lobe some lithium grease onto the shaft and work it into the chamber via the shaft (don't try shoving it into the hole). That should free the actuators right up.

This would be a good idea if I intended to keep the 6 port engine. The actuators themselves are fine, the front rod is stiff (LOL) but moveable while the rear is completely seized.

Originally Posted by vex

This doesn't make sense...

You know what I meant! This is my first rotary so I'm still used to diagnosing issues in piston-engine-speak.

[vex]

Originally Posted by infernosg

How does an engine coked in oil look normal?! 105k miles is also hardly what I consider a "long life engine". Hell, I've only put 5k miles on it in nearly two years of ownership. This also isn't a show car. As long as it (was) running I didn't really care how clean it was inside or out.

Tongue, meet cheek.

[infernosg]

Originally Posted by vex

Tongue, meet cheek.

Don't you have a RX-7 to work on?

Anyhow, started pulling the engine apart today. Only got to the intermediate iron before I decided to stop so I could clean the garage to better organize parts. Only thing I found I can't explain is pictured below:



Any explanation? Aside from that everything looks good - really good, but soaked in oil...

[infernosg]

Started the teardown last night. Found something interesting. Note the line for the oil injector on the primary port for the front rotor. That couldn't've been good for the engine!

[vex]

Eh, that's not as bad as it could be. I'd be a little more concerned if the primary oil line was broken (the one that sits directly on the rotor housing).