Hey all,

Yesterday after running errands (normal driving, no runs/etc) for lunch break, I noticed while "cooling off" idling in Florida's shitty hot weather right now...I noticed a puddle of coolant under car (not overflow side...but almost directly below middle of the radiator position) and my coolant buzzer went off for first time ever (probably not the only time ever too...yay, fun! ). There is also some minor splashes (not bad but it is noticeable) of dried up coolant on the IC piping, lower intake pipe for primary turbo, and some on my GReddy elbow...I assume (I hate presuming but will inspect) b/c the coolant may have splashed around thus the fans sucked the coolant towards the surface of engine (as the position stock radiator fans are...not VMIC or FMIC setup). So I refilled slowly with some distilled water and was able to stop (!) the coolant buzzer sound and light to go off. Later, I drove home fine (25 min) in the already busy 5 o' clock traffic w/o any signs of overheating or buzzer going off again. Got home, parked in garage, turned on shop fans, inspect coolant one more time and seem fine w/ coolant almost to F mark. Anyhow, I believe I have a cracked stock OEM radiator (plastic side tanks) or a worn/busted coolant hose somewhere near the bottom near my radiator. I did recall slowly driving over a bumpy road near the post office (errand) so not sure if that had any play?

Fortunately, I drove my DD to work today. When I got back home from work...I checked my overlflow reservoir and it isn't even enough coolant to mark "Empty" (!) and my Pettit AST is half full. I peeped around with a flashlight and none around AST or any hoses near engine surface...however I can tell the plate/undertray was some liquid obviously coolant. I haven't had chance to completely look deep but hoping this weekend I can invesigate further. I will probably remove the front bumper for easier inspection. I'm pretty sure it's along the line of a busted coolant and/or radiator hose or radiator itself....mainly because of the minor coolant sprays/splash on engine surface and my other "positive" indicators as noted below. But just wanted to see what everyone thought.

Positive Notes (knock-on-wood, ha!):
1) Idle is been perfectly stable and fine at 700rpm-900rpm as it has been ever since I got car (2 years ago)
2) No puff of any colored smoke (including white) at all either at start up or after a drive
3) Car starts fine on first try...no sluggish, miss fires, etc.
4) No overheating...temps is average 95C/203F
5) This pretty much happened all in 1 day
6) Radiator cap and AST caps "appear" fine but I will go ahead and replace anyways
7) See my complete mods: https://www.rx7club.com/vbgarage.php?do=view&id=70583

Thanks everyone for reading and/or input,
Tam

 

^ I meant to say above I checked coolant level almost 4-5 hours after driving home from work the coolant was almost at F...not 5 minutes after getting home from work. But somewhere between 9pm thru 5pm next afernoon...coolant started to leak as it can be seen on middle portion (damp) around lower undertray area (if viewing from above) and on the ground.

 

Stop driving your car until you find that leak. Seriously, you've been lucky and all it takes is a few seconds for the coolant to leave the system once the failure point reaches critical.

Best way to pin point the leak is to get a coolant pressure tester. Rent, buy, or borrow it and make sure you get the mazda adapter. If you don't want to spend the money to buy then take it to a shop and get it tested. I couldn't imagine it costing much more than $50 to $75 for the test.

I've had everything coolant related go on my car. Some hoses went with in days of each other. The leak in the middle could be caused by a few items, Radiator, Lower coolant hose, water pump, thermostat housing.

You also mentioned water marks on the elbow. There are only two hoses on that side of the engine bay, the throttle body coolant line, and the heater return quick disconnect located below the oil filter.

Most failed hoses only leak once warmed up to temp and most of mine never even leaked to the ground, just pin holes that eventually give up. Also, if prior to this leak, you've ever thought you smelled coolant while driving but then it went away, you weren't dreaming.

If your hoses haven't been changed in the last several years I strongly recommend giving Ray at Malloy Mazda a call and ordering his coolant hose kit. One of the best purchases I've made from him. You'd never believe how many hoses there are on these cars.

Good luck.

 

i see in your mods u dont have a ecu!! lol im also waiting for fdnewbie to come out with his vmount kit...seems like its taking forever!!!!! listen to car hugger he knows from experiance with cooling problems with his car

 

thanks for the info Car Hugger. i checked the TB line and around...none. Looking at it from the way the dried up coolant on engine surface is (IC, elbow, lower intake pipe) ...the directional appears to be almost directly around the lower radiator hose...anyhow, I'm about to hit the garage and check out and around. Will remove bumper for deeper look too. Will keep everyone posted.

FD3S2005, in regards to ECU. I've seen and read many recommended chronological mod list and my ECU is still fine with my setup. But pretty much anything I upgrade next will definitely and must include ECU (PFC)...like IC, Hi-Flow, etc.

 

There's no need to remove the bumper. It takes about 20 to 30 minutes to remove the intake, IC and battery tray. Once those are out you will be able to see all the radiators hoses. There are some return lines, one to the radiator from the AST, one to the overflow from the AST that could also be the culprit.

FYI it is possible to remove the radiator from the car from above. I've done it 4 times on my car, including yesterday when my drain **** broke off inside the radiator while flushing and replacing the water pump, thermostat, etc. The most important part is to gently lift the AC out of the way as you remove the IC ducting keeping an eye on the aluminum lines making sure they don't start kinking.

 

^ yah, the radiator and surrounding areas is where I really wanted to take a closer look at and figure easier to view around w/o bumper on (if end up removing radiator from bottom). I removed all the pipings and surrounding parts a few months back to polish so I'm about to go back and remove again.

 

Update:
Topped off the car and started up to warm temp (to find leak) and found out both radiator hoses are leaking (I can see it clear as day dripping under car)...upper is minor but the lower one a lot more (a lot of dried up coolant). It's leaking through sub frame area. After removing some parts for easier access...I can feel the radiator hose...especially the lower hose wet/drip. Plus, I can see how the fans (when on) can sling the coolant around on engine surface from both upper/lower hoses.

Also FYI and side notes, idle/startup is fine...no white smoke...and did champagne bubble test which checked out fine too. So fefore I go out to buy replacement radiator hoses...do you think i should do a pressure test anyways for other possible leaks? For reassurance, I plan to pick up the complete coolant/radiator hose kit from Ray next week.

--------

Here is a pic of actual leak (appears more of distilled water) on cardboard layout...just imagine this layout directly under radiator. leaks no where near overflow reservoir which is a good sign to say the least.



Clips of the actual leak (ignore my shop's fan sound in bg. Started to remove undertray too but decided to record first):
http://www.tamcai.com/rx7/leak01.mpg
http://www.tamcai.com/rx7/leak02.mpg
http://www.tamcai.com/rx7/leak03.mpg

 

^ one last note...the other stain on the ground that is not on the cardboard (as seen in video #1 mainly behind cardboard) is oil over course of past few months yet it still looks fresh.

 

I had coolant coming down the lower radiator hose - turned out to be a leaking water pump seal. The coolant ran down from the pump and looked at first as if it were coming from the lower hose.

Dave

 

Hey Dave, did you car experience any type of above the normal/elevated water temp or overheating since your water pump/seal was the culprit?

 

if you need the upper rad hose i think i got one or 2 lying around somewhere

 

No. I caught it so early (there was just a quarter-sized puddle under the car) that there was no significant coolant loss. It happened late last fall when the weather was cool. I did not drive the FD again until after I had replaced the pump.

Since your coolant loss is pretty slow, I would suspect the pump seal. Most other leaks (hose pinhole, cracked end tanks) lose coolant much more quickly.

Dave