91 wont stop leaking antifreeze

[jsweeter]

I have a 91 4x4 4.0 L V6 with 128,000 miles and it will not stop leaking antifreeze. This winter I noticed it leaking from the top of the radiator, leaving puddles on the ground. Replaced the radiator and the truck is still leaking antifreeze but cannot find out where, not dripping at all. The hoses are tight to the water pump and thermostat housing, and the heater core. The oil is not showing signs of antifreeze in it. Any ideas? thanks in advance.

[Headnsouth]

Is the rad cap new? Let that truck sit in the driveway idleing and let it get good and hot. Then with a flashlight start checking the connections. Most times small leaks won't show up until it gets good and hot.
good luck

[jsweeter]

cap is a new vented one. When it was leaking before changing the radiator it was leaking when it was cold not when hot. Now I cannot tell. It may be the water pump.

[backerm1]

do you smell it? how much is it leaking?

[jsweeter]

yes you can smell it after a couple minutes or so of it running, not in the cab just outside. Leaks about the whole overflow out about every 2 days. Used to take about a week to run the overflow out now it is getting worse since replacing the radiator, less leaks I guess means more pressure at the leaks yes?

[toddler62]

After the truck is warmed up shut it off and look underneath it at the bottom side of the waterpump there is a weep hole there. If it the waterpump is leaking this is where it normally leaks and with the car shut off after warmed up it will have the most pressure built up so it will probably show signs of leakings. if not leaking there look all around the outside of the engine hoses where the heads meet the block where the intake meets the head.

[backerm1]

might have to get it pressure tested. It could be a leaking head gasket. do you see white smoke in the tailpipe?

[jsweeter]

Tonight I got out to my truck from work and it had a little puddle under the radiator again. In the middle of the radiator where no hoses or lines are connected. Smelled it and it is antifreeze but it was only a little. Pressure test is what I am going to get next week. Yes it is blowing white smoke out the tailpipe but it also has an exhaust leak after the cat. Couldn't tell if it was anything as it is colder than hell here in michigan. 13 degrees.

Wouldn't a leaking head gasket put antifreeze into the oil though?

[jsweeter]

Got an appointment for it on Thursday. Learn more then.

[bigj4664]

i have an 88 ranger and i would check the freeze caps/plugs. That is what i am going through right now i bought the truck and he said it was leaking cause of the heater core come to find out it needs a freeze plug due to weak anti-freeze. Mine was a big leak when i got it but he said it started as a little leak

[jsweeter]

Taking it in today for a pressure test. When I shut off the truck you can smell antifreeze in the back of the truck by the tailpipe, I think its the head gasket. Find out more tomorrow.

[DonSor]

Yup! Sounds like you got a head gasket problem. Coolant gets into your compression chamber after you shut down the engine. That's because the cooling system has momentary higher pressure than your combustion chamber. However, as soon as you start the engine, it is the otherway around, that is, you combustion chambers has much higher pressure than the cooling system blowing out whatever coolant was on the chamber/s out the pipe.

[jsweeter]

Well guys bad news, the heads are cracked. Looking into getting new or rebuilt ones. Is there a difference in the 90TM to the 93TM heads? Found some rebuilt ones on ebay (item # 280209916913) and some new ones (item # 260225228830) they are about the same price at 390 and 410. Which ones would you guys prefer?

Thanks in advance for your advice.

[backerm1]

damn, don't know about the 4.0Ls. Have you checked the forum part section?

[DonSor]

Both heads were cracked? Are you plannning on keeping the truck for awhile? If so it may be prudent (if affordable) to pull the engine out and do a "long block" job. Afterall, after you remove the intake manifold and the heads, everything else is staring you right in the face. Also careful about used blocks from websites. You could get one with hairline cracks and you're right back to where you were. Good luck.