The Elusive Coolant Leak
 

Alright, so I started up the 7 this morning and my coolant light/buzzer came on so I added what anti-freeze I had lying around and topped it off with some water. When I had the car inspected the coolant system wouldn't hold pressure, it was ever so slowly leaking somewhere. Checked under the car: nothing, scanned the radiator for a good 45 minutes: nothing, listened to the engine with a stethoscope: nothing. Anyone got any ideas or troubleshooting tips as to where the coolant's going?

2 main options.
The TB coolant lines. The behind the block heater core lines.

Any smoke?

Could be getting pumped into the motor, check your oil to see if it looks like chocolate milk.

No smoke and there's nothing to indicate a leak behind the block; everything's bone dry.

The oil's light brown and see-through so I don't think it's leaking in to the engine. I'm stumped. :confused:

Maybe I should go down to Checker and some of that metal stuff you add to the coolant and it's supposed to stop minor leaks... dunno if it's safe to use on rotaries or not though.

Check the carpet under the dash. Look for any wet or discolored areas. Maybe heater core or more likely the coolant hoses where tey attach to the core.

There's nothing with the carpet. My Toyota had a leak so I'm paranoid about wet carpets and check them every day. I'm trying to bleed the coolant system right now and see if that fixes anything by some off chance. At least it'll show me how long the system will last before it starts complaining again.

Also, this might have something to do with it. I have to park outside on the driveway since the garage is occupied by other cars and it's at a really steep angle. Maybe the coolant could be pooling somewhere?

I guess water pump weep hole :)

So... probably nothing to worry about, just constantly check on?

Of course you need to keep an eye on her, and if she gets progressively worse you're going to have to find it :)

Eh, I'm used to the 'yota where all you had to do was change the oil and it'd go forever. My first car ('88 VW Rabbit) was really high maitenance so I guess I should flip back over in to that mode. ;)

If all your hoses look fine and your radiator isn't leaking check your water pump. Might be a bad gasket. I had the same problem and it turned out to be leaking out the bottom of the water pump. And I really hate that fucking buzzer.

If you can't find a visible leak obviously it is something internall unless, it's a pinhole leak like I have had many times. When you have a pin hole leak your system has a vent through which it will loose pressure mut nut spray out water, basically steam can come out through these samll "pinholes" but nothing is actually visable. I have had this problem many times in the past. Check each and every water hose for bloating or expansion and check where they connect for any signs of excessive corrosion which can be caused by steam. If all else fails try the infamous radiator sealer trick. It can't hurt any.
Good luck!!!!!!!

Damn is everyone having coolant issues this month lol....

Do you smell any anit-freeze during or after driving??? Usaully.....you would want to check for a leak about 5-10 miutes after driving it. I had problems with mine and would notice leaking not right afterwards, but 5-10 minutes later....these FC's do strange things.....try it.

Nah, there's no smell or anything (my nose is keen for these things after owning several beaters) and I checked it every 2 minutes after driving it hard around town. So, it's either some pinhole leak somewhere or my water pump. I'll stop by Checker tomorrow to pick up some of that no-leak stuff and see if it does the trick. Thanks everyone!

Another possibility is the gasket (or lack thereof-some previous owner thought RTV was sufficient) between the water pump HOUSING and block. The coolant is under very little pressure as it leaves the block and enters the water pump housing, that a small leak from old gasket or idiot using just rtv, that the coolant leaks and basically evaporates on the hot block so you dont get a puddle til it gets really bad. My theory on why just RTV is bad in this spot is the added vibration of the housing from spinning parts will eventually crack the RTV.
I had this prob at end of summer and took me forever to figure out this is where the prob was. Got the wife to cut me out a new gasket out of proper water gasket material and all is well.

At this point there are two opposing methods:

1) Keep looking & as it gets worse, you will find it.

2) Add AlumaSeal of BlockWeld to stop it for now & hope you don't get stranded when it lets go.

BTW - I have had great results with RTV - never a problem.

RTV in a lot of places is ok, but I truly believe this is not one spot that it is up to the task. In fact there are 2 washers that space the housing to level for the required gasket. As well as I mentioned this spot is under greater vibration stress due to housing running water pump and fan. For the cost of a gasket, (or make your own as I did out of true water gasket material all of 2$ of material) I think it is good insurance.
Also exhibit A ...the RTV in fact failed on my car as previous owner choose to just use RTV and drippity drip...

well said
you should check your rad caps because if there are not sealing properly the coolant can boil and escape as steam
but i wouldnt use any additive or stop leak in the coolant system as its just a bandade for the problem.

Yeah, I'll order a new cap capable of a higher pressure and see if that helps any as well.

Sorry for the bump but...

DUDE YOU JUST MAY HAVE SAVED MY CAR! :)

I've been wondering why my car is loosing coolant. I have NO leaks, and NO smoke what so ever. None on startup or anything (and i pre-mix, no smoke :) )

I bought a gasket set off e-bay, and it didnt include the small 4" x 2.5" in or so gasket from the block to the wp housing. So, I put maybe a 1/32" to 1/16" layer of RTV on both surfaces, let it "dry" (to rubber) then put a small amount on the wp housing and bolted it shut. This was with black rtv, not that shitty blue stuff. I should have used the high temp stuff, but thats all I had, and I HAD to get the car running.

I'm going to check this out, and order a new gasket. Hopefully this will get rid of it. I thought it was my coolant cap, so I replaced it... No go. Still loosing it somewhere.

ok, how much of a pressure drop are we talking about?


3 PSI in 10 minutes? if it is over this point then i would say you have a leak, if less then your tester is bleeding off. i have used snap on, matco, mac, etc testers and i have yet to find one that holds pressure for more than 10 minutes unless you are using one with an air pressure source.

just something to chew on. :)


you all may not even have a leak...