Topic: Coolant Reservoir

[chrisfranklin]

I've been refilling my coolant reservoir pretty constantly for the last couple of years.  About every other time I'd check it it'd be empty. 

Based on my experience with a previous vehicle, I figure there's a leak in the reservoir or hose.  I had a leak in the coolant reservoir on a crown vic I used to have and I had to replace the reservoir on that one; the leak on that one was pretty easy to spot. 

So I went ahead and decided to spend a few bucks and got another reservoir for my 4banger, even though I hadn't sited any leaks or fluid on the ground (take that back, maybe I have and wasn't putting 2 and 2 together -- maybe my head was on something else and I wrote off the fluid on the ground I saw as from somebody elses vehicle). 

I'll get some new hose for it locally.

Thermostat is stock, radiator on my 4banger seems likes its in good shape and is consistently topped off when I check it 

Question though is, is there any other plausible reason besides a leak in the hose/reservoir that would account for an empty coolant reservoir? 

(I've pretty much ruled out smart dogs with straws trying to drink coolant out of my reservoir when the 4banger is parked)
 

[neale_rs]

I had a Bronco II that always needed coolant with no visible leaking.  It was pressure tested and nothing was found. I ended up selling it but I now think it was a head gasket leak.  It would probably be a good idea to pressure test the cooling system and check the compression of the cylinders.

[Jeffy]

The radiator cap?  The springs on the overflow valve are set to 13#, 16#, etc...  If the spring rate is too high it might not flow back into the overflow.  I'm gonna guess you haven't tried opening the radiator cap with it empty.  If there is pressure and it starts leaking out all over the place them that's probably what's going on.

[chrisfranklin]

The radiator cap?  The springs on the overflow valve are set to 13#, 16#, etc...  If the spring rate is too high it might not flow back into the overflow.  I'm gonna guess you haven't tried opening the radiator cap with it empty.  If there is pressure and it starts leaking out all over the place them that's probably what's going on.

That's interesting, Jeffy. Don't have a definitive answer on whether I've ever opened the radiator cap with the reservoir empty. 

But I'm pretty sure I have since I know I'd be thinking: "well the reservoir is empty, hope there's still coolant in the radiator...better check that out." 

I do recall opening the radiator cap one time while the engine was still warm and fluid shot out of the radiator (bad move)

I think the radiator cap is probably the same one that's been on there since 1993-94.  They wear-out, maybe?

I was also thinking that all the airbox/air intake removal and installation  had, over the years, maybe damaged the hose to the reservoir (probably the original '94 model hose, too).


I'll keep what you mentioned in-mind, Neale.  Thanks.

[Torch_Ind]

check the water pump weep hole for signs of leaking, also have had lower rad hose leaks that I double clamped and it sealed up. and yes as above head gasket leaks or cracked block could cause but general if your putting a lot in it has to come out somewhere "tail pipe / over filled oil" for it to be internal problem..

pressure testing is a good way to go about it.

I know my YJ over flow goes empty from time to time I think cause it's not a sealed unit like newer style vehicles have were the catch tank is pressured with the cooling system. and I noted that it mainly goes low when I"m off-roading.. but my rad never goes low. 


How fast does it go low? daily, weekly, monthly???

[chrisfranklin]

I'm not driving my 4banger much, but I seem to be noticing the reservoir empty roughly every other time I pop the hood.  So this might be every 1-2 months. 

When I see the coolant reservoir is empty, I fill it up again.  Then after probably a couple of times driving over the course of several days or maybe a week, I'll check the reservoir again; but then I'll find that the fluid level is good and where I left it last time. 

So then I'll forget about it, a month or two will pass and while I'm at a gas station checking the oil, I check the coolant reservoir and see that it's empty! 

Right now the check list is looking like:
1) Reservoir/hose, radiator hose leak or attachment problems
2) Radiator cap
3) Weep at water pump
4) Pressure test, gasket leak   

[sharpxmen]

I'm not driving my 4banger much, but I seem to be noticing the reservoir empty roughly every other time I pop the hood.  So this might be every 1-2 months. 

When I see the coolant reservoir is empty, I fill it up again.  Then after probably a couple of times driving over the course of several days or maybe a week, I'll check the reservoir again; but then I'll find that the fluid level is good and where I left it last time. 

So then I'll forget about it, a month or two will pass and while I'm at a gas station checking the oil, I check the coolant reservoir and see that it's empty! 

Right now the check list is looking like:
1) Reservoir/hose, radiator hose leak or attachment problems
2) Radiator cap
3) Weep at water pump
4) Pressure test, gasket leak   

most common reason for this is radiator cap not holding pressure (Jeffy mentioned it) - reason behind it being that if there's no pressure or low pressure the coolant will evaporate more easily and will be lost in vapor form thru the overflow tube and thru the coolant reservoir. Buy a new cap (the reason can also be a faulty check valve on it or even the gasket) and see if it still happens, if it does you'll need to find where the leak is. Keep notes of when you checked the coolant level and the results (cold and hot once a week to start with, more often won't hurt) and see what the results are.

[neale_rs]

I would put #3 first (free), then #2 (cheap).

[Jeffy]

You can rest a pressure tester BUT I think it's the cap.  Pressure is what allows the coolant not to boil off.

You should be able to spot a weeping water pump.  You will want to check it after getting the engine up to operating temp.  At operating temp you should also be able to find any leaks as the pressure should rise.  If the cap is bad and isn't holding pressure, you'll see the coolant start flowing out of the radiator into the overflow.  If the radiator is always low then that would be my first guess.

[chrisfranklin]

I've kept an eye on things a little more closely as of late and I'm seeing a nice big old puddle of green pool up below the front of the engine.  Radiator hoses are in good shape and connected and it's looking like its probably the water pump seal (ticks me off because I had to replace the water pump a few years back -- I installed one of these jobs http://www.quadratec.com/products/51212_58.htm; maybe should have stuck with oem).

[chrisfranklin]

I've kept an eye on things a little more closely as of late and I'm seeing a nice big old puddle of green pool up below the front of the engine.  Radiator hoses are in good shape and connected and it's looking like its probably the water pump seal (ticks me off because I had to replace the water pump a few years back -- I installed one of these jobs http://www.quadratec.com/products/51212_58.htm; maybe should have stuck with oem).

Actually, I was reading these flowkooler pumps are supposed to have a lifetime warranty, so if the pump is the problem I'll send it back for another

[Bikerjr1]

I had the exact same problem you are describing.  for the first year or so I'd have to add coolant, never could find a leak.  Then one afternoon I cranked it up and the radiator started leaking.  The joint where the top of the radiator tank and the core join together is where it was leaking.  From the look of it after I pulled the radiator it had been seeping out for a long time, but not enough to hit the ground or anything else.  I'm just glad it failed in the driveway and not out on the road.
JR