So my rx8 runs fine. I see and feel no issues with the car. However every time after I drive I pop the hood and their is brown bubbly coolant coming out from the engine coolant container. Engine temp seems fine. Is this just a matter of doing a full coolant flush?

2nd issue I find is when I'm going in 3rd or 4th and at 40mph and I push the clutch and brake down to 20mph it has trouble switching to 2nd gear at times giving me a gear scraping sound (which is obviously bad I'm damaging the transmission) but it gives this sound even with the clutch fully pressed down.

Any suggestions for these 2 issues?

Thanks

Brown engine coolant coming out of container

 

Mmmmm, milkshake!

Bad news, friend. You need a new engine. That is classic coolant seal failure, in normal cars it would be head gasket failure. Your coolant system has a leak, and the pressure of combustion is forcing oil and gasses in.

If youre mechanically inclined, you can remove it and send it off for rebuild. A rotary rebuild is a lot different from a piston engine rebuild and not recommended as a first time project. You can send it to Kevin at rotary resurrection, or trade it to Mazda for a reman engine.

Does the transmission have any problems going from first to second? Grinding when you put it in gear, even without a load sounds like that gear is trashed. How many miles on the transmission?

 

Well ****.

Is the only solution to replace the engine? How much would that cost me? Are you saying I have the option to trade it in to mazda for a new engine? What exactly is the issue? How did this happen what is happening and what will go wrong if I continue to drive the car?

The transmission issue has been resolved.

 

For one thing, seeing that goo coming out on top of the overflow, rather than the overflow tube, tells me that overflow bottle is cracked at where the rad cap sits. It's not unheard of.

Second, with the bottle cracked, the coolant can't pressurize, which means it can't adequately cool the car, which could have caused an overheat that ruined a coolant seal inside the engine or warped parts of the engine.

That's my theory from the info provided. Is you oil also milky like this? If it is, that confirms that engine has to come out. If you do nothing, oil and coolant will continue to mix until you either overheat once more for good or a bearing seizes.

If you can confirm the overflow is cracked, it will need to be replaced as well. The whole cooling system and the oil coolers, if the oil is also milky, will need to be flushed/replaced to get that milkshake out of it before new engine goes in.

You can't trade Mazda for a new engine, but they'll sell you one and take this one in. Total cost should be around 5-6k. If you go with Rotary Resurrection, or another rotary rebuilder (if you let us know where you are, maybe we can point one out), it should be cheaper. Cheapest but least reliable option is to swap in a used junkyard or JDM import engine, but demand proof that it's in good health.

 

thanks for the input,

this has only started happening recently, the engine heat as shown on the dashboard seems okay, also oil is not milky and has no fat or foam on the dipstick. If this is the case does that mean I still have time to "save" the car (and its engine) from more permanent damage? What do I need to do? Just replace the cooling system and oil coolers? how much would that run me for? (Parts and then labor estimate). If the engine overheats would it warp or melt and be completely destroyed? so I should get on this ASAP correct? Is there any more info I could provide that would help you in diagnosing and advising my situation?

 

The oil being OK means you don't have to worry about the oil coolers, so that's positive.

If you have oil in the coolant, as it appears you do, the damage is already permanent and the engine has to come out. However, if you want to try to squeeze every last mile from it, the first step would be to check if the overflow bottle is actually cracked and replace if so, then flush the cooling system and refill with fresh coolant. See how long it takes it to get back to the same place.

Just to be crystal clear: if that coolant is that colour because it contains oil, there is no permanent fix short of replacing the engine.

 

So flush and replace the coolant and replace the overflow box if its cracked.
So if i'm driving my car and I want to squeeze every last mile out what warning signs would I get that the car is failing? would the engine heat dial on the dashboard be way overboard? Currently whenever I drive the engine heat dial is slightly befor dead center leaning towards the left or colder side. Does this mean that the damage that has already happened hasn't completely unfolded yet but will overtime if I continue to drive? Will I begin to see the dial move more to the hot side etc.?

So what led to these events (sorry don't know too much about this stuff)
Overflow bottle cracked so coolant couldn't cool engine so engine warped destroying a seal so oil is leaking? So the actual engine is damaged and cannot be properly cooled?

So for now fix these things see how long it takes for the coolant to go brown and just make sure the engine doesn't overheat?

In total if I wanted to fix everything I'd have to fix or replace

Coolant box
Overflow box
and Engine.

right?

thanks

 

Again, the first step is to confirm the overflow is actually cracked. I'm going off one picture and a short description here, so please don't take this as definitive diagnosis.

There are other reasons you may have oil in the coolant, like if someone added it. Maybe that goo is not even oil (although it sure looks like it). Maybe someone added an additive like WaterWetter or a stop-leak chemical, which can have that effect. The coolant is supposed to be a clear green colour.

So how about we refine this to:

1) confirm coolant bottle is cracked and replace if so. this should be easy, just open the cap while the car is cold and look at it.
2) drain the coolant, run a radiator flush solution through it (maybe a few times), refill with Mazda FL22 coolant ONLY. No other coolants in there.
3) see if the new coolant starts to get murky like this and it the car experiences overheats or difficulty starting when cold

 

This stuff doesn't look that oily to me...

I know some old coolant can be a disgusting brown colour, so definitely flush your coolant first with genuine Mazda FL-22.

And yeah, looks like the bottle itself is shot. Mazmart carries replacement ones. You might also wanna check the coolant reservoir cap, which may also have been damaged(although I think the new coolant reservoir comes with a cap).

Also, just because the needle doesn't move doesn't mean your engine is fine. At least in S1 RX-8s, the temperature gauge won't move until your car is overheating by a bit. Hook up an OBD II reader and read the temperature, and then compare that to the normal operating temperature.

 

I live in Ann arbor Michigan. Wondering if you could point me in the right direction if I ever have to replace the engine. For now the plan is just to replace and flush the coolant and over flow box and oil cooler maybe and see how it goes, check engine temp with an OBD and see how its going. Some others have said that the coolant may just be old so won't hurt to just go slow. I appreciate all the advice you have given me!

 

If that were my car, I would send a sample of motor oil to Blackstone for analysis. They can tell you exactly what is in it, which will tell you a lot about the condition of your engine.

The next step is a cooling system pressure test. Find out if anything is leaking, and where any leaks are. This is an inexpensive test for a shop to do, or you can borrow the tools from most auto parts stores.

Assuming the coolant seals in the engine hold pressure, I would replace the radiator, the coolant bottle and cap, thermostat, and as many hoses as possible. A replacement radiator is something like $80, and the rest of the parts are relatively inexpensive as well.

Then, a thorough flush with distilled water should be performed to clean out the water pump, heater core, and anything else that might be holding that sludge. Actually, do this, before you take everything apart, then do it again, after you install the new parts. Drain the sludge, flush the system at least twice with distilled water, replace everything, flush again. Distilled water is 80 cents per gallon. Use a lot of it.

From there, I would fill with Mazda FL22 or Zerex Asian and watch it very closely for signs of degradation.

 

The rotary expert in southeast Michigan (from my understanding) is Chip's Motorsports in Warren: chipsmotorsports

Follow the list above to the letter. An oil analysis is never a bad thing to do, regardless of engine condition. And if you're going through the trouble of replacing the entire cooling system, you might as well go for upgrades if it's in your budget

If you're in need of help with anything from someone local, feel free to shoot me a PM.

 

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