LittleZ360

So I have an 04' 6spd, 65k miles, maybe 10k on the replaced motor.

So for the last week or so, my coolant light has been coming on occasionally and then would shut off while driving. I checked the coolant level each day it happened and it never changed.

Now today I was driving, stopped at the bank with the engine just idling, and just before pulling away, the temp needle was a little past halfway (a few notches hotter than usual) then went down to normal as I drove away.
So I get home and check the level and it was like a full inch below the fill line all of a sudden. So I topped it off and let the engine run while I searched for a leak and couldn't find any leaks anywhere.
I then took it for another drive, maybe about 4 miles, and down the road at the gas station, it was just sitting idling and I came out and the temp needle was a few notches hotter than usual again... I drive away and it goes back to normal again...
So arriving at home, I let the car cool down and check the coolant level and it was about 1/2" lower than where I had just topped it off at!

My exhaust doesn't smell any more foul than it usually does (i'm running without a cat) and there's no blue smoke or anything... so I don't think it's the seals. But if its not the seals than there's gotta be a leak... which can't be found anywhere in the engine bay or on the ground.

When I take the radiator cap off it lets out a pretty good poof of pressure even after it cooled down for a couple hours as well... so I'm kinda stumped

Anything else I might be missing before I load up my coolant with dye?

LittleZ360

So last night I added a good amount of "Stay-Brite" UV dye into the coolant reservoir and then took it for an aggressive drive with the coolant right at the F line.

Came back after about 20 mins of driving, and the level was about 1/4" below the F line after cooling back down. Brought it into the garage, closed the door, shut off the lights and worked the UV light all around and under the engine bay, every crevice I could peak at I checked and I couldn't find a drop of the UV dye. Nor can I see any just plain waterspots (my engine bay is usually quite clean).

There's no smoke coming out of my exhaust, there's no film or oil in the coolant reservoir, and there's no sludge on the dipstick- just clean oil...

What the heck am I missing?
I suppose I can get my oil tested for contamination, but I gotta say on the dipstick it looks fine.
Its not runny, or milk shake looking like you would normally see from oil/water mix... Smells like earthy oil, not sweet like coolant.

The engine hardly has 10k miles on it. Coolant was flushed once after the engine replacement. Maybe around 4k miles ago.
Oil changed quite regularly, and the oil level is checked and adjusted as needed on a regular basis.
Still tho, I guess it's possible the seals are faulty and just haven't dumped out completely yet.
In which case... I wonder if I can still point my finger at the dealership for giving me a faulty engine (was replaced just before the warranty expired)

200.mph

iTrader: (9)

did you burp your cooling system of all air? if you start your car from cold with the rad cap off does the coolant bubble?

ShinkaEvo

iTrader: (3)

Ur coolant reservoir is loosing pressure, causing the coolant to leak from the reservoir led and evaporates while your drive.
Try to replace the cap, it still loosing coolant, you'll need to replace the reservoir.

j9fd3s

the rotary doesn't have a head gasket, so its actually pretty hard to have the oil leak into the coolant, or vice versa. so a failing water seal, won't contaminate the oil.

did you check around the top of the radiator? i find that the cooling system is relatively hard to check on these, because the radiator is kind of buried

LittleZ360

I pulled off my air box and batter box today. I couldn't see the entire top of the radiator but most of it, and where the hose leads in on the top, this doesn't appear to leak at all.

I will go out there in a bit after the car cools back down and try looking for bubbles in the reservoir with the motor running.
So should it bubble or not bubble? :/

I'm assuming any bubbles would indicate air in the system... right?

ShinkaEvo

iTrader: (3)

Air in the system and pressure are two different thing.
You can have air in the system but still holding the pressure.
You'll need something like the pressure tester to test out if the reservoir is holding the pressure or not.

You can also get radiator cap for cheap tho.

LittleZ360

By radiator cap you mean the cap for the reservoir?
Btw, I ran the car w/the heat on with the cap off, no bubbles or burps, although the car was on level ground, I don't have access to a jack and jack stands at the moment. (apartment)

LittleZ360

Okay so after the car was sitting for some time, I went back out do check the coolant level, and HA! I have a puddle of coolant under my car! YAY!!! Something found!
This is the first time Ive seen any coolant outside of the reservoir so atleast I know there's a leak and my engine isn't burning it up or anything.
I'm guessing the leak was slow and got faster, cuz it certainly didn't have any visible coolant before, maybe evaporated before it could be seen.


Now I can't find the leak for the life of me... I busted out the UV light as I still have that dye in my coolantIf I look under the grill I can see it dripping slowly from the top of the radiator mostly... then also a tiny spot in the middle of the Rad but It doesn't seem like enough to be the source.

After removing the Airbox and the battery box and their trays, I can tell for sure it's not the hose on the top of the Rad leading up to the Reservoir, that's clean and dry... I can't see any coolant anywhere from above the engine bay with these parts off... the fan blades are clean as well as the face of the radiator pointing up toward the hood. The fan shroud is clean too.

The reservoir's overflow hose is dry inside and there's no coolant where it's directed so Its not overflow...

Its mostly pooled up in the tray for the front lip on the passenger side.

When I run the car, the dripping stops. Now that it's cooled down for about 10 mins, it seems to begin dripping a little again.
Whatever it is, it got worse, as it wasn't visible before, but was obviously losing coolant.

There's no dripping or anything near the engine, whatever it is, it's up in the front by the Rad somewhere...

I'm kinda thinking it's like the top outer rim of the Rad, but not sure...
It's mostly on the passenger side of the Rad, but a little on the other side too. I think it may have just worked a stream towards the drivers side.

So now I suppose I gotta keep moving stuff out of the way until I have a full view of the radiator.
looks like I would have to remove the reservoir to get a better view which will spill a bit after disconnecting that bottom hose.

Problem is, I leave town tomorrow afternoon for the weekend and it's going to be bothering me until I get home Sunday night... Thankfully I don't have to drive.

Anyhow... I would appreciate any thoughts and thank you so much for the support you've given already. I'm sorry if I come off as a bit of a noob but I don't trust shops around here and I prefer to get the "know how"

Looks to me like I'm looking at a new radiator when I get back, but I'm not going to jump to that conclusion until I've covered everything else.

I'm sure it'll be bugging me all weekend so I'll be checking this for responses. So put in your two cents if you have the time! Thanks

LittleZ360

I'd just like to add, I'm so happy that missing coolant wasn't going into my engine... I'm also glad I noticed it before trying to take my car out of town this weekend.

j9fd3s

sounds like you need a radiator, they will leak between the end tank and core when they go bad

ShinkaEvo

iTrader: (3)

If you are gonna replace the radiator, might as well replace the hoses at the same time, just to be on the safe side.

LittleZ360

I hear ya. Looking around briefly, I see there's replacement (1row) radiators on Amazon.com going for under $100... are these **** radiators or possibly worth a shot?

I'll def. replace the hoses in the process. I'm tired of replacing something every other month on this car...

Also, I may go ahead and pull out my SSV for a cleaning while I have all that stuff coming out of the way, as I suspect it gets hung up every once in a while even though the solenoid, actuator, and vacuum all checked out fine.

Thanks guys!

sweatr

If your doing the work, it may be possible to replace the plastic end cap rubber gaskets?. I have never done it on my eight but on other cars in the past. Saved a few bucks.

LittleZ360

I'll look into that when I get her out. Thanks for the tip!

J_Ro

So I feel like I might be on the same boat at the same time. Kind of funny that I found this actually, I was about to start a thread about my problem. Kudos to me using the search option.

So anyways, a while back I was going down the HW at 75ish (I was late for work) and my coolant started spewing out onto my windshield. I pull over and check things out and it seemed that the coolant was coming from the over flow hose beside the cap. This is just what I guessed though, since I had pulled over and turned the car off it stopped and I was just left with pools of coolant. My step mother came and gave me some bottles of water so I could fill it up and see if the problem continued. It didnt and I continued to work.

Around a week ago I was driving down the road and saw my temp going up, once again I was going around 75ish so I figured this was going to be round 2. I eased off the gas and the temp went down to just below half was on the gauge (which is usually where it stays in my 8). I went directly home and it seemed I might have been slightly low on coolant so I put some more in it and left it for the night. The next day I was going down the same HW and once again going around the 75-80 mark and it began rising. It will go 2-4 clicks beyond the coolant temp symbol it the middle of the gauge, and once I let off the throttle and it fell back just under half way.

Basically when I keep the rpms around 4k or over for a while the temp will quickly rise to a few clicks over half way on the temp gauge. Once I let off it will go down to just below half way. I see now leaks and I really havent noticed being low besides that one time when I put a bit more antifreeze in it a few days ago.

If anyone has any ideas please post them. Ive got class starting soon and Im trying to figure this out asap.

Thanks.

LittleZ360

As I've just been wrapping my head around the cooling system recently, I'm certain there are others that can off a little more help in your case. However...

Im thinking the water pump may not be keeping up and the radiator boils up and spews out the overflow tube on the reservoir. Maybe you could zip tie a little bottle under the overflow tube and determine if that is indeed where it's coming out. If so, you may want to redirect that overflow tube until you figure things out so it doesn't spatter all over the place and onto wires n such.

Or... You may have a leak in the system that's allowing air to get sucked in and I believe that would throw off the level in the reservoir.

I still haven't dived into my car to take my radiator out yet, waiting until I clear out the garage. Im quite certain at this point that my problem is the radiator, but haven't seen the exact point of leakage yet.

Our circumstances are a bit different, as my coolant leak is only apparent when the car has been off and cooled down. Also, mine started to get hot when I was sitting at idle then cooled down when I applied gas, where as yours got hot while cruising and cooled down when you let off the gas.

Here's a link to the rx-8 (and rx7) shop manuals Foxed.ca - Mazda RX-7 Manuals
they may be of some help if you're just getting familiar with our cooling systems.

Good luck and share what you find!

RIWWP

iTrader: (2)

J Ro:
Agreed with LittleZ, it sounds like your water pump is having trouble pushing coolant through the system. This could be a number of possible failure points, but they pretty much all suggest that you have some sort of cooling system restriction and/or blockage. Thermostat, clogged radiator, clogged line, etc...

I'd recommend starting to replace stuff until you solve it, or just replace everything all at once. OEM radiators are under $200 from Mazmart.



For both of you, get several (4-10) feet of clear tubing and connect that to the overflow. Run the tube up the driver's side of the engine bay and out through the gap there, make a loop and zip tie the loop near the base of the windshield wiper arm. Run the excess anywhere you want after that to keep any coolant off wires and paint, etc... That way you can see almost exactly when you start dumping coolant. Some delay, still has to fill up the tube, but faster than waiting till you stop somewhere and pop the hood. It also confirms that it's the point you are dumping coolant from, if you aren't too sure about it.

LittleZ360

Yeah I already ruled out the overflow on mine. Like I suggested to him, he could zip tie a bottle under the OF tube, if the bottle accumulates any fluid that that's where it's coming from.

I'm leaning towards a full aluminum radiator, but then again, the stock radiator failing after 9yrs isn't bad for a Chicago car... While I'm at it I'm probably going to order the highflow water pump from mazmart. It would only make sense to tackle the hoses while I'm at it, which brings me to my next question...

I see most silicon hose kits are just 2-3 hoses for the radiator. Are these the only ones necessary to replace while I'm going at the radiator or should I go with the full oem replacement hose kit?

So far I haven't found any of the red/blue/black silicon hose kits for the entire system, just the oem replacement has all the hoses it seems. Anybody know otherwise?

J_Ro

I was on my way to work a few days ago and it was acting normal. I drove it hard as much as I could because I wanted to see if I could get it to over flow, but it never went over half way up the gauge. I was guessing it might be have been gone but it came back the same night while I was doing the daily redline.

Also, I noticed a jump in power at about 5.5k rpm. This has been going on for a while, but maybe it has something to do with this? Idk, just thought I'd throw that in there haha. Any info on that would be appreciated as well. I've also noticed that it kind of idles rough at times. Mainly at lights. I was looking around and found that I would probably need to get a new O2 sensor. Sound right?

04, MT, everything under the hood is original besides the obvious stuff that needs to be changed every few thousand miles, still on OEM cat as well, 84000 miles.

I was telling my dad about the problem I've been having and he didn't really know how to help so he called Mazda to see what info they could give up. He talked to some chick and her son had apparently had an 8 so she "knew what she was talking about". He told her my issues and she said replace the thermostat and if that don't work work then I might have a blown head gasket and this means that I will need a new motor ASAP. Lol wut? She must have been talking about the apex seal or something? Or maybe she's clueless, who knows lol.

We're changing the thermostat tomorrow along with flushing the coolant. The whole 9. Ill probably put WaterWetter in the coolant as well. It couldn't hurt. Maybe this will help, either way it's a good first step. I just checked and my coolant hasn't leaked so I gather that this is either poor coolant flow or something else.

J_Ro

Is in the shop for coolant flush and new thermostat. Hoping for the best even though I'm not expecting much.