Leaking coolant...

[FurrMan]

I just reworked my AMC 258 i6 / 4.2l with a new water pump, hi flow radiator, electric fan, and thermostat at 195 degrees. My setup has been working fine for the past two weeks but today I noticed a steady drip of coolant from the back of the motor until the block cooled down. I still have plenty of coolant fluid in the system so I feel like I have some sort of a pressure leak. Has anyone dealt with this before? I just ordered a slew of parts to do a nutter bypass and tfi with mc2100 upgrade. I sure would like to know I have everything sealed up before I start with the conversion.

 

[Torxhead]

I don't remember if there are soft plugs behind the flywheel, which would probably be the worst case. First you should look at the heater hoses, especially the one going into the rear of the intake manifold. Otherwise you are going to have to trace this one down.

 

[mtnwhlr]

You might want to replace your radiador cap. You may be getting to much pressure. The only thing that would be leaking in the back of the motor would be a freeze plug. But i would check the cap or replace it.

 

[FurrMan]

Thanks, I don't have a leak on my intake manifold where the hoses are but I think the water is coming from the front of the block and sliding down the oil pan. I lowered the Transmission doing my lift and the engine is at an agle. But if there are plugs in the rear of the motor then want am I looking at repair wise? Btw I have a brand new rad cap, possibly do need to get another, what do you recommend?

 

[mtnwhlr]

If it is a freeze plug you will need to replace it.

 

[FurrMan]

How do I replace the freeze plug, sorry to sound ignorant but I am really just a weekend wrencher so I'm in uncharted territory here.

 

[Torxhead]

Knocking out a freeze plug is quite easy, and they come in standard inch sizes. After draining the radiator coolant they can be removed by punching on any side of the plug and it will force the oppisite side out, then removed with pliers or vise grips. In the case where they can't be whacked at with a hammer, there is an expandable version.

 

[FurrMan]

Do I need to pull the engine out for this? Where are the freeze plugs located. It's interesting that it only dribbles when hot but has no leaks when sitting cold or running not up to operating temp. I have some bubbling and hissing ( when hot) from the therm housing and it appears that the leak is pressure driven. A patient of mine told me about a pressure pump and gauge for the rad to test for leaks. I will start there and work my way to the back of the block. Thanks for all the help...just can't figure out why I may have pressure issues in my coolant system.

 

[xena1]

Dont think its a pressure issue, you just have a leak somewhere. Might check temperature sending unit on rear of intake manifold.

 

[Torxhead]

To find it there are various methods even including some that are quite high tech. The easiest way is just to see where it is leaking from along the engine block(If that is where you suspect it is.) with a warmed up engine and radiator cap in place. Although it might involve cleaning off the engine if need be. I would hope that it would not be coming from the bottom of the Transmission housing which could indicate a removal to get at it. But I would hope you could easily find it by tracing down the source.