mobilehippo Posted July 27, 2015 Share Posted July 27, 2015 I just got back from a 2000 mile trip on my 78 Toy. She ran great. However, after every 300-400 miles I check her coolant level in the reservoir and they are near dry which is really scary. Her thermostat never shows she's overheating and I didn't get any signs of overheating while driving her even when I drove an hour in city traffic. There are no visible leaks nor see any white smoke coming from her engine. I'm thinking the culprit might be that when I bought her, the previous owner had lost the reservoir cap, the cap where you put the coolant, not the one by the radiator, and had put a juice jug cap on it instead. I can screw it on pretty tight but obviously it's not original and maybe its evaporating through there? I've also read it might be a head gasket issue? Quote Link to comment Share on other sites More sharing options...
Bob C Posted July 27, 2015 Share Posted July 27, 2015 It sounds like you have a leak inside your engine. It must be small, at least for now. Quote Link to comment Share on other sites More sharing options...
jjrbus Posted July 27, 2015 Share Posted July 27, 2015 I had a 98 Ford Windstar, best vehicle I ever owned. I had the van for 14 years and put 198,000 miles on it. I had to watch the coolant. It was usually down, but never found a leak and no water in the tranny fluid or oil?? It would not go down at times and then others it would go down faster. Never did figure it out?? Jim Quote Link to comment Share on other sites More sharing options...
Maineah Posted July 27, 2015 Share Posted July 27, 2015 It does not evaporate any faster than water does. The only way it gets back into the radiator is when the engines cools. Try checking the radiator when it's cold a couple of times and see where the level is. You may invest in a new cap they are not expensive. Quote Link to comment Share on other sites More sharing options...
Totem Posted July 27, 2015 Share Posted July 27, 2015 I would card board it underneath and let it idle in the july weather a bit and shut it down. if you see coolant spots on the card board you can trace it. could be pinhole leak in rad, dry rotted hoses (most likely culprit) etc etc. Quote Link to comment Share on other sites More sharing options...
DanAatTheCape Posted July 28, 2015 Share Posted July 28, 2015 I would take the reservoir out and see if it has a small leak, ditto for the hose to the radiator. I would also do the cardboard trick to see if you can ID a wet spot. Antifreeze can "leak: internally - one common issue is a head gasket that allows coolant to migrate into a cylinder where it goes out the tailpipe as steam. Not sure if either engine (4 or 6 cylinder) have coolant passing thru the heads on toy's. Instead of keeping the overflow reservoir full, let it go a little longer and repeatedly check the radiator WHEN it is cool. If the coolant was drained recently air in the system may be working it's way out - and that leaves a void for coolant to fill. If that is the case it will eventually stop taking coolant. Quote Link to comment Share on other sites More sharing options...
5Toyota Posted July 29, 2015 Share Posted July 29, 2015 yes they do have coolant in the heads . 1978 that should be a 20R if you ever have to remove the head . one of the big problems at least back a while replacing the head gasket with a FELPRO and I had this happen to me the felpro was not made the same as the factory head gasket was sold as PERMERATORQ put on tork forget about . NOT so the factory head gasket torq down run eng for 800 900 miles then RETORQ THE head they never blew unless you overheated it some how. those felpro would do good to last 2 years and would blow at anytime for no reason . a Toyota mechanic warned me and that is what I found . another thing I have seen is HEADS so corroded out from not changing antifreeze they are aluminum that they begin to leak into the motor. if you smell antifreeze in the tailpipe it will be a head job. Quote Link to comment Share on other sites More sharing options...
5Toyota Posted July 29, 2015 Share Posted July 29, 2015 forgot to say check water pump around the bottom side if it shows any drip behind the pully wiggle the fan in out side to side any slop there or drip replace pump. and I have had 2 20R water pumps with many miles of use freze up solid. Quote Link to comment Share on other sites More sharing options...
Maineah Posted July 29, 2015 Share Posted July 29, 2015 There is a valve in the bottom of the radiator cap it is a round disk that is how the coolant gets back into the engine when it cools. Driving, the pressure lifts the spring in the radiator cap and the expanding liquid is forced into the tank if the pressure does not raise enough it may not force the fluid out into the tank. Keep an eye on it at the radiator cap and see what happens to the level when it's cold if it remains the same your fine but if it’s all ways low then there is a possibility of a head gasket or external leak. If there is a good shop near you they most likely have an analyzer that checks tail pipe emissions that same tool can check for hydrocarbons in the radiator if there are any the head gasket is leaking. Quote Link to comment Share on other sites More sharing options...
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