Where to look for not so obvious coolant leaks

[Blueman2]

Good news! -- not so obvious coolant leaks found

The 4Runner (96 Ltd auto 4x4) just absorbed another 3 quarts of coolant in less than a week.

I checked the exhaust, no smell no white smoke
No leaks or spots on the ground under or around truck
Automatic trans, but coolant and tranny oil are both clear so no pink milkshake (yet?)

I found a couple threads suggesting examination of the heater hoses near the passenger side frame rail and also the heater supply up near the firewall. Are there any other spots that could be leaking without leaving a visible trace?

This has me flummoxed for the moment. I have not pressure checked, need to cobble up (kinda like WECSOG) some kind of adapter for the rad filler neck to attach air.

Thanks for any info or suggestions

 

[kball]

3 quarts in less than a week? That's a lot of fluid to not show any signs. How's the carpet inside the cab?

 

[TheDurk]

My 4Runner has never leaked. But I had an old BMW 735 that drove me crazy. Turned out the leak was on a hidden spot along the return hose from rad to reservoir. This hose is not involved in a pressure test and coolant only runs BACK to the reservoir when the car is good and hot--therefore usually when it's moving. So you never saw a leak. I only spotted it by pulling over when the car was really hot and looking under the hood carefully.

Not saying this is your problem but it's something to check.

 

[BrianSD_42]

some basic suggestions:

a) determine if it leaks even when you aren't using it, eg. don't drive it for three days.

b) park it on a cloth or something that will show a sign of the leak. pavement doesn't always show coolant leaks.


If you do both of those and still have no leak then it is getting burned up in the engine. Not much mystery here.

:keyboard:

 

[Stick Figure]

This is where test equipment comes in handy. Not always (as mentioned above) but often a pressure test will find the leak.

If the pressure test revealed nothing and I saw no pink trails (another good benefit to the factory coolant), I personally would pull the spark plugs, inspect them, and then do a leak down test (w/ the radiator cap removed) and look for bubbles in the coolant. Just don't stand over the radiator, when you pressurize a cylinder i've had it geyser on to me doing that. lol

 

[4Running Daily]

Ya be careful, my friend actually has burns all over his arm from doing a compression test incorrectly.

 

[Blueman2]

Thanks all for your suggestions, I am sorry for the delay in responding.

The coolant is actually the green stuff rather than red but will look out in spots mentioned.

In the past when I have had a vehicle burning coolant, the exhaust has had a very distinctive odor. I don't smell it with this one but I will keep it in mind and try the leakdown test. Need to find an adapter for the plug threads.

No reports of leakage into the cab, carpet is not soggy but will check more closely.

Will also warm it up and check the overflow hose and bottle

Will try the cloth on the ground trick

Thanks again for suggestions, will advise of results.

 

[alexchannell]

Check the rear heater hoses. These are known to rust.

 

[Blueman2]

Good news!

Had my son start his truck and leave it to warm up. It ran about 10 minutes and I still could not find a leak anywhere. I wrapped up my work as he was heading out with a pal. As he pulled out of the driveway I saw it. A puddle under the passenger side rail. I stopped him and crawled underneath and found where the two pipes turn up into the body was dripping. I wiggled the little cover/shield and the drip increased.

I'll have to figure out what parts need replacing. But at least the issue is known now.

Thanks for all comments and suggestions, as usual I got great info and starting points.

 

[TheDurk]

Good news!

Had my son start his truck and leave it to warm up. It ran about 10 minutes and I still could not find a leak anywhere. I wrapped up my work as he was heading out with a pal. As he pulled out of the driveway I saw it. A puddle under the passenger side rail. I stopped him and crawled underneath and found where the two pipes turn up into the body was dripping. I wiggled the little cover/shield and the drip increased.

I'll have to figure out what parts need replacing. But at least the issue is known now.

Thanks for all comments and suggestions, as usual I got great info and starting points.

That's the feed line to your rear heater. You can bypass at the engine compartment or fix it with flexible coolant hose and run fine. The actual hard lines from the dealer are pretty expensive if you go that route but they are an option. Searching will get you details on all this.

 

[dbole]

leaking rear line

That's the feed line to your rear heater. You can bypass at the engine compartment or fix it with flexible coolant hose and run fine. The actual hard lines from the dealer are pretty expensive if you go that route but they are an option. Searching will get you details on all this.

I had the same issue wiht mine, and rather than paying the $100 for the new line, I just put brass plugs on the rubber hose ends and clamped them off.

 

[PitbullRescuer]

I had the same issue wiht mine, and rather than paying the $100 for the new line, I just put brass plugs on the rubber hose ends and clamped them off.

Why? Mine were leaking too. I cut the metal lines, bought 20' of rubber heater hose, ran it from the rear heater to the good metal lines I cut on the fire wall and all good. Cost me maybe $20 and my rear heat still works. I don't understand why people just loop it and loose the rear heat.