Modern Vespa

Alright, looking for some automotive wisdom from MV....

My car (Ford Escape, 2003, ~108,000 miles, owned since new) has a small coolant leak. But the only symptom is a drop in the level in the reservoir. There is no sign of a leak anywhere outside of this. The leak is perhaps 4 fluid ounces per week, sometimes less. I put a new exhaust back half on this spring, and the only residues in the tailpipe is a very slight, dry, black sooty sort of thing. Barely comes off on a fingertip. I changed the oil a couple of weeks ago, and there was no sign of coolant in there. I have checked all the hoses, water pump, radiator, and reservoir overflow, basically any place where one could notice evaporated glycol stains that would be visible from outside, and can't see anything. I have not stood behind the car when starting it up yet, but I have idled it for some extended time from cold in the driveway and do not smell or see anything coolanty coming out of the tailpipe (just water, nothing slimy or stinky, just normal exhaust).

I have never changed any of the hoses nor the water pump, though I have changed the coolant. Oh, and I also recently did the spark plugs and other than a bit of oil in the plug enclosures on two of the 6 plugs, no sign of any ignition issue or contamination on the plugs. Plugs were replaced after coolant started going away.

So at the moment I have to think tiny leak of one of the cylinder head gaskets, that only lets coolant out when hot.

Other than this one thing the car drives well.

Two questions:
1. Any thoughts on where the leak may be?
2. Any thoughts on those sealants that can be added to coolant systems to stop leaks?

I'm not normally big on "As Seen On TV" magic pills in opaque boxes or bottles, but if there is someone on here with some knowledge about these things, who could recommend a good stop leak chemical if such a thing exists, I'd appreciate any advice.

Cheers,
Sully

Wondering if there was anything equivalent to the UV/fluorescent dye used to detect leaks in air conditioning systems, a Google search found that there is such a thing at auto parts stores. Might try that.

So some dye and a UV light then....
Many thanks.

Howdy
I assume no anti freeze odor inside the car? Which could be heater core.
I have seen water pump leaks that are almost undetectable so the dye could be a good try.
Ken

Thank you. Looking like I'll go get some dye and stuff to see it....
And fortunately, no sweet smells in the car.
Replacing a heater core just doesn't seem fun, not at all.

If its not a heater core problem- like kpgo said you'd smell it- I'd say your radiator is certainly old enough to have a pinhole or two in it. The stop leak products do work. My family has used Bar's Leaks since at least the 1950's. My father spent 40 years running an automotive machine shop and always recommended it. Very easy to see their products on their web site.

If you don't see any coolant on the ground you may have a small leak or a internal leak (place some paper under your car over night and see what and where it drips out the next day)

Past time to replace all your hoses

Use the Bar's leak only as a last resort (get you home or to the radiator shop)

You're on the right track with the UV dye to find where the leak is. If a hose or clamp, simply replace. otherwise: This. If there are no puddles then you probably have a tiny leak thats only rearing its head when the radiator gets to certain temperatures. Stopleak may catch it. if not, you could try j-b weld steelstick.

Thanks all!

Dye, light, and glasses are on order. Might come in handy for AC repairs, some day....

There are no puddles, drips, or any external signs. But, it is a very small leak so could perhaps be a pinhole in the radiator or bad seal in the water pump.

I'll give the dye a go, and if something visible externally is the source, will replace that and the hoses (oh, and clamps ). Time for a new water pump anyway, and thermostat too.

Did you check that you don't have coolant in your oil? I'd bet it's either a head gasket or the gasket between the head and the intake manifold. 4oz per week isn't much do you may not see residue on the plugs.

-craig

Yup, changed the oil two weeks ago, no sign of water in there.
I'm just holding out hope it is something other than a head gasket.

I do plan on buying a new car within the next 6 months anyway, and at this rate if I check/fill every two weeks it is quite safe. I'd just prefer to fix it so I can sell with good conscience.

Just saw where you are planning to trade cars...
I was going to say when did the timing belt get replaced?
Many times they advise you to replace the water pump at the same time they do the belt...

A leak that small will probably only leak when the motor is hot and the cooling system is pressurized. It will likely evaporate before it makes it to the ground. The best way to find a small leak is to pressurize the cooling system when cold. It takes a special kit with a hand pump and various adapters to fit different radiators. It has a pressure gauge on it. You pressurize it with the pump and if it has the smallest leak it will soon show up as a drop in the gauge. Not too much longer the leaking coolant will make it to the floor since it's not evaporating because of the heat of the motor. If the pressure drops and you pump it back up several times and no leak is still apparent it's a good chance it's going into the oil. You also use the same tool to test the radiator cap, which also could be the problem. You can get the tool at Harbor Freight for ~$50 or just let the man handle it.

This particular car has timing chains. So no problems there.

Well, I have UV dye at home that I am going to put in tonight. If it is a pinhole in the radiator I guess I expect a sort of splat/airbrush stain downwind. Otherwise I'll just look for bright spots with the UV light I also got. Here's to hoping I see the light!

Make sure to shine the light on the exhaust too.

So the UV dye survives the combustion chamber? I didn't think it would. Handy.

As per the tappet brothers of Car Talk fame. There was some discussion of adding a raw egg to the radiator.

Use to listen to them, they were funny, but didn't have a clue how to fix a car newer than 1970.

I would use the pressure method. Advance auto parts loans tools.

John

Bars Leaks is effective for everything except water pump seals. Many decades ago a certain UK manufacturer who shall remain nameless added it on the production line as insurance against core plug leaks and porous castings. Given the age of your vehicle a kill or cure alternative would be to use a radiator flushing agent which would probably turn a small leak into a bigger one that you could find and fix.

You mean the old school method the dye replaced?

ALL manufactures use a stop leak product during production.
GM requires adding after intake manifold or head gasket replacement on most vehicles.

Alrighty, so I put 1 oz of UV dye into the system on Tuesday, and now we wait. My wife drove the car about 150 miles or so yesterday, and no sign of drop in level of coolant. So this may take a while. The longer the better as far as I am concerned.

I'll probably check it tonight with the UV light just for fun. It's dark out when I get home anyway....

Yes it tickles my frugalness, borrowed pressure tester and all. I suspect if it is slowly leaking into the oil I'm not sure you will see the dye in oil.

Set up the garage floor with cardboard, pressurize the system and leave it over night.

Just for the record I like analog meters too.

John

Problem with a pressure tester is no one checks the operating pressure the system should be pressured to and they put in too much, and any system will leak with enough pressure.

I haven't spotted anyone mentioning it but the pressure cap should also be checked or replaced. Most pressure tester kits do have an adapter which allows the cap blow off pressure to be tested and although modern systems have a catch tank arrangement this does not always prevent gradual loss. Obviously I'm not familiar with this particular vehicle.

Yes, roadster is correct. Often leaks such as the one described by the OP is nothing more than a duff coolant pressure cap. This doesn't allow the coolant to reach it's predetermine running pressure, allowing the coolant to evaporate out of the system without leaving a trace. This should always be replaced on any motor if no visible leaks are spotted.

That's a very good point , I think the moral of what your saying is if you don't know what your doing go pay someone. The problem is most guys know less than us at the shops.

I agree with Roadster and Stromrider

John

Also worth checking the engine block core plugs, especially behind the block in the hard to see places. I had a core plug leak very very minor amounts of coolant over a six month period before I found it. Nothing ever present on the garage floor, no evidence that could be easily seen. The exhaust manifold and downpipe covered the area where the core plug was situated making it almost a no go area. But after putting the car over the pit and getting underneath, there it was. Traces of coolant that evaporated before it hit the ground. Once the system cooled down and the pressure had gone in the system there was no leak.

Block core plug, we call them freeze out plugs.

John

Ok I see that. Glad you know what I mean though.

No I am saying use the modern test equipment (Dye) available instead of an old school pressure tester that still has you looking for a had to see liquid, so a dye is still needed in most cases.

The UV dye would not have helped in my own case. It still would not have been visible behind the engine block. Very close to the bulk head and hidden by the exhaust manifold, down pipe etc. Very hard to shine a UV light up there. Had to find my leak using mirror and very small torch. But the standard non UV dye in my coolant was just visible. I pulled the engine and fitted a new core plug (freeze out plug) since the leaks always get worse and it's easy to do. Coolant sealants are really just a valuable but shorter term measure.

Lots of helpful replies, so I thank everyone.
I put dye in about a week and a half ago, and since then the car has been driven a couple hundred miles or so.
No sign of leaks anywhere. Engine bay, exhaust, anywhere on the block or near the radiator. Also no drop in coolant in this time either.

I'd almost rather see something, then I'd have something to fix....
Oh well. Just have to keep driving it I guess!

Cheers,
Sully