95 Ranger 3.0L losing coolant somewhere somehow

[98v70dad]

My 95 3.0L is losing coolant and I haven't been able to pinpoint the leak. The truck has 106,000 miles on it and is located in Atlanta where vehicles can last forever if taken care of. Here's what I know. 1) There is no coolant in the oil. 2) There is no oil in the coolant. 3) For what its worth it passes the rubber glove test 4) No cloud of white smoke from the tail pipe. 5) Engine runs smooth 6) Heater works fine. 6) I bought a UV light and put some dye in the coolant. There is a bit (tiny) of a leak at what I've heard is a common spot at an upper timing chain cover bolt (passenger side) but I would describe it as a weep more than a leak. 7) The radiator doesn't have any apparent leaks. It's the original radiator. 8) I'm not sure about the water pump. I haven't checked it thoroughly because the night I did the dye check it was raining and I didn't want to lay in the mud to get under there. In a lifetime of owning cars I've never had one fail as early as 106,000 miles but it IS pretty old. 9) The engine runs at the normal coolant temperature. 10) All of the hoses are in good condition - no apparent leaks - they have been replaced once in the life of the truck.

Anyhow, any help would be appreciated. I fill the overflow tank and a few days later its almost empty after driving less than 50 miles. Yet, there is no coolant puddle in the driveway. Not even any drips. I thought maybe the overflow tank has a crack in it but its dry under it. I have two trucks and this one doesn't get driven a lot but I'd like to get it back on the road because it doesn't eat gas like my full size 4x4.

 

[Brain75]

Just to eliminate the easy, sounds like you have looked for low/no pressure leaks very thoroughly, how bout high pressure leaks? - let it idle and check for
leaking while running, take it for a drive to get up to thermostat open, then pull over and look for leaks hot + running + while the thermostat is open.

Another place to check is the heater core - which means HVAC set to heat and fan anything above "off" to make sure coolant is flowing through the core, check for wet passenger floorboard as well as fluid on the ground.

Any gurgling to indicate air is getting in the system?

 

[Brain75]

If you have a parts place close I suppose the easier way to do it would be to rent a pressure test kit from parts place and then you can pump it to whatever the cap is rated at (no more) and look for it with pressure but no noise of the engine/danger of the moving parts.

 

[SenorNoob]

When you run the heater does it smell sweet? Seems you've checked everything else.

 

[98v70dad]

Just to eliminate the easy, sounds like you have looked for low/no pressure leaks very thoroughly, how bout high pressure leaks? - let it idle and check for
leaking while running, take it for a drive to get up to thermostat open, then pull over and look for leaks hot + running + while the thermostat is open.

Another place to check is the heater core - which means HVAC set to heat and fan anything above "off" to make sure coolant is flowing through the core, check for wet passenger floorboard as well as fluid on the ground.

Any gurgling to indicate air is getting in the system?

Thanks. To add to the story, the truck has been sitting in the driveway since Christmas because I just didn't have time to deal with it at the time. It also needed brake pads and the pads were down to the wear indicators so I figured I would let it sit and get to both problems when the weather warmed up. 70 degrees here today so.... Anyhow, I tell you this to say that months back I Iooked for leaks after letting it warm up and driving about 20 miles. Nothing. I did not use the UV light at the time. However even when I check it in the driveway (like today) its with the engine running, coolant temp at normal operating temp (not cold) and all the hoses rock hard so I know coolant is circulating.

I've had a heater core flood my old 96 Volvo before (filled the footwell) so I already checked for that . Usually a leaking heater core is either obvious because of the puddle or you get a sticky film on the windshield or even a sweet smell. I'll check again but last time I looked I had none of those.

No gurgling. I know what you're talking about my old mercury sable gurgled.

 

[98v70dad]

When you run the heater does it smell sweet? Seems you've checked everything else.

No. I've had a heater core fail in another car so I knew to look for that. Sorry I forgot to mention it.

 

[98v70dad]

If you have a parts place close I suppose the easier way to do it would be to rent a pressure test kit from parts place and then you can pump it to whatever the cap is rated at (no more) and look for it with pressure but no noise of the engine/danger of the moving parts.

I have considered doing that. Advance Auto Parts rents tools but I've hesitated to do it because nobody in there knows anything about cars and relying on them for anything is ALWAYS a mistake. The last time I rented a tool from them the guy on duty didn't even know they rented tools. Then he rented my the wrong thing and by the time I left I was frustrated and pissed off. Do most kits have a plug/cap that will fit our ranger's radiator?

 

[Brain75]

Well my next diagnostic thought (other than renting the pressure kit) would be to park it on a clean spot, fill it up, note the exact height of the tank with a piece of tape, let it sit a couple days and then check the radiator to see if it is low as well as the overflow - if your cap is working right and you have a radiator leak the overflow should stay full (the leak will suck air in from the atmosphere as it drains fluid long before it hits the 16psi of the cap)... if the radiator isn't loosing anything and the overflow isn't loosing anything as long as it sits then at least we have eliminated those spots to look - then we go back to the engine.

I have never used the kits, which is why I didn't think to mention em in my first post... so far every time I have had a leak it has been the water pump (and always a chevy and always before 75k mi.... with the exception of my '48 which had a leak at the t-stat housing [alu] because the PO cranked it down way too tight and cracked the housing)....

 

[98v70dad]

Well my next diagnostic thought (other than renting the pressure kit) would be to park it on a clean spot, fill it up, note the exact height of the tank with a piece of tape, let it sit a couple days and then check the radiator to see if it is low as well as the overflow - if your cap is working right and you have a radiator leak the overflow should stay full (the leak will suck air in from the atmosphere as it drains fluid long before it hits the 16psi of the cap)... if the radiator isn't loosing anything and the overflow isn't loosing anything as long as it sits then at least we have eliminated those spots to look - then we go back to the engine.

I have never used the kits, which is why I didn't think to mention em in my first post... so far every time I have had a leak it has been the water pump (and always a chevy and always before 75k mi.... with the exception of my '48 which had a leak at the t-stat housing [alu] because the PO cranked it down way too tight and cracked the housing)....

I've done what you suggest and it seems that its the overflow tank that empties (drains). This afternoon the tank had about 1" of fluid in it (almost empty) but the radiator was so full that a little spilled out when I took off the cap. I haven't driven the truck since before Christmas and the I filled the overflow tank to the line when I parked it. I believe the radiator cap is working right because its new. I replaced it when I did the flush and fill about a year ago.

I've suspected that there is a crack (or some other leak) in the overflow tank for a while but I haven't seen one when I looked for it. The plastic stuff does eventually fail here in the South because the heat bakes it to a point of being brittle. I've considered buying a new tank because they aren't that expensive. The last time I did a flush and fill I took the tank out to clean out the nasty crud in it. The hose at the bottom didn't feel that tight to me. So, maybe its that.

Regarding the pressure test kit, I actually tried to rent one months ago and the guy didn't know what I needed ... he had several to pick from. Since I didn't know what I needed either I just passed on it. I figured I buy a kit off of Amazon but again I didn't know if the plugs that come with any of them are the right size for the ranger. Its still on my list of things to try.

 

[Brain75]

history of the "overflow" tank in 2 min...
back in the 40's you didn't fill the radiator 100% full, you left space at the top for it to expand - no overflow tanks at all.
then came true "overflow" tanks - they burp into it and never suck back out of the tank. (the hose entered at the top of the tank)
and now we have "surge" tanks (everyone except the manual in your glovebox still call it 'overflow') - the coolant expands into the tank and suck back out as it cools.

The big take away though, the cap is rated for like 16psi, as long as it is cold and the pressure is below that it neither sucks nor spits. once the pressure gets higher it spits out to the expansion and as it cools it will pull some back in (this is why the hose from overflow tank to radiator connects at the bottom of the overflow tank).

if your overflow tank empties all by itself without running then you got a leak in just about only 3 or 4 places...
1) the hose that goes to the cap/top of the radiatior at that end
2) same hose at the tank end
3) that hose somewhere in the middle (look for rabbit damage if it was some low draggin curb scraper like my GM with goofy routing)
4) the tank itself.

If you ever got really cold - colder than what the coolant or your windshield washer fluid is rated, it will probably crack the tank/windshield fluid side of that same tank along one of the casting seams and have a slow piddling leak all the time.

 

[98v70dad]

history of the "overflow" tank in 2 min...
back in the 40's you didn't fill the radiator 100% full, you left space at the top for it to expand - no overflow tanks at all.
then came true "overflow" tanks - they burp into it and never suck back out of the tank. (the hose entered at the top of the tank)
and now we have "surge" tanks (everyone except the manual in your glovebox still call it 'overflow') - the coolant expands into the tank and suck back out as it cools.

The big take away though, the cap is rated for like 16psi, as long as it is cold and the pressure is below that it neither sucks nor spits. once the pressure gets higher it spits out to the expansion and as it cools it will pull some back in (this is why the hose from overflow tank to radiator connects at the bottom of the overflow tank).

if your overflow tank empties all by itself without running then you got a leak in just about only 3 or 4 places...
1) the hose that goes to the cap/top of the radiatior at that end
2) same hose at the tank end
3) that hose somewhere in the middle (look for rabbit damage if it was some low draggin curb scraper like my GM with goofy routing)
4) the tank itself.

If you ever got really cold - colder than what the coolant or your windshield washer fluid is rated, it will probably crack the tank/windshield fluid side of that same tank along one of the casting seams and have a slow piddling leak all the time.

I think I'll take the tank out and inspect it closely. A new tank and a new hose is an easy fix. A leak in any of those places you noted is the best case scenario for me. This was my dad's truck and he didn't believe in preventative maintenance. I'm not convinced that it isn't something more serious but fingers crossed. That said, my cars all last several hundred thousand miles and I'm the mechanic. I'm not great at it but usually good enough. Your point about freezing is a good one. There was a time that you couldn't get wiper fluid in Atlanta that was rated for freezing weather. It freezes here every winter most nights in January. Just last week it was around 15 degrees F at night. Apparently withholding wiper fluid with alcohol in it helped the city meet some emissions requirements. Currently the wiper fluid in the stores is appropriate for our temperatures. Anyhow, there's a good chance the wiper fluid compartment froze at one point because the truck is parked outside.

 

[Brain75]

Remember that big freeze in Austin in 2021, everyone without power... yeah I was there, I didn't loose anything, but everyone around me, all my friends were without a lot of stuff. Several lost the windshield fluid bottles, same reason the only thing you can buy in the store was "summer" blend rated at 32f...

 

[98v70dad]

I got some great comments yesterday. Most of them except the pressure test I had already accomplished. Does anyone else have some other suggestions?

 

[98v70dad]

I'm planning on doing some detailed inspections and an exhaust gas combustion test today. I'll update what I know afterwards.

Update: The exhaust gas test came out negative. The timing belt cover gasket is leaking from the top passenger side. I can't find a weep hole on the water pump to look for drips there but it's sort of irrelevant. If I replace the timing belt cover gasket I will replace the water pump since is almost 30 years old, has a little over 100000 miles on it and it has to come out anyhow. I see minor seepage from a bunch of hose connections including the expansion tank and thermostat housing. As far as a pressure test goes I am hesitant to do that. If I have gaskets (and radiator and heater core) that are about ready to fail but are still holding up and may work for another couple of years I don't want to push them over the edge. I usually only drive this truck short distances and I think its worth the risk.

Question: I will be replacing the hoses too since there's going to be a mess. The truck still has the original hose clamps installed. I've read not to re-use them. I've used the stainless screw clamps that you can get about anywhere before and had no problems with them. However, as a engineer who specs parts for airplanes, they have always seemed like cheap crap to me. Are there better alternatives that don't cost a fortune? The european style are pretty nice but they cost a lot and its a nearly 30 year old truck.

 

[01Edge3.0]

I'm new here, haven't even written my introduction page yet, but your title caught my eye. I'd had a similar leak in my 2001 3.0 engine that drove me crazy for several years. It finally showed itself this past summer during a particularly large and busy mileage span while we were moving. I neglected to keep an eye on the water until the radiator blew out. I replaced the radiator, and lower hose. When I filled it and did a test run, there was the leak - now a spray, coming out of that little "T" fitting above the water pump where the temp sensor mounts. The "T" had been weeping all those years, but only under pressure while driving. After replacing that (not an easy chore), no more leaking issues. I've attached a picture, but you can barely see the fitting in question. It is the brass colored piece in the center with the temp sender. The leak is on the bottom where it tees off to a small hose that is part of the lower radiator hose. By the way, I bought that part on Amazon, Dorman #47993. Half of the front of the motor has to be taken loose to get that little bugger out of there. Anyway, something to check for. Sorry this is so long.