Coolant overflow tank leaking

[mknherhappy]

The coolant overflow tank is leaking on my 88 MJ. Is there a temporary fix for this? I ordered a new one, but was hoping to take mine in for a exhaust fix over the weekend.

 

Was this a common problem with the tanks?

 

Thanks again for your help.

[mvusse]

The tank is pressurized to 13psi when the coolant is hot, same as the rest of the system. Depending on where it is leaking, it isn't likely there's a way to fix it that will hold under pressure.

[BLHTAZ]

Correct...that is an integral part of the pressurized system so the only fix is replacement.

 

Be sure to search a little on here for instruction on how to properly bleed the air out of the system when you change it or you will be replacing it again shortly when it overheats and blows it out. Ask me how I know... :oops: ;)

[Luvtohunt]

How do you properly bleed the system? I looked all over and did not find any directions or mention.

 

Appreciate the info.

[BLHTAZ]

The easiest way that I have found is to park the truck with the front down hill. If you don't have a place to park it with the front end lower than the rear, then jack up the back end as far as possible.

 

Once that is accomplished, let it set for a few minutes to get all the air to the rear of the head and then make sure the pressure bottle is properly filled, locate the temperature sender in the top left rear corner of the head, unplug the wire and unscrew the sender from the head. Keep it close as you will not need to have it out long, but all the air will burp out of that hole and then coolant will flow out. when the air is out, quickly put the sender back in.

 

Mine bled out and worked fine in one try. I have seen a couple that had to be done a second time, but once is usually all it takes. It should be obvious that doing this with a cool engine is best. ;)

[Luvtohunt]

Could you post of picture of the tempature sender, or describe it?

 

Thank you for the information.

[BLHTAZ]

The temp sender is in the red box. The thing you see above it with the green plug is the MAP sensor and it makes it much easier to do this job if you take that off of the firewall and move it out of the way so you can use a ratchet & extension to get to the temp sender. when you remove the plug from the temp sender it will be a small brass unit, but I can't remember what size socket fits it right now. A couple turns with the socket and then you will want to use your fingers to finish the job so as not to drop it wen it comes out ;) .

 

>>This is not my engine, but just a pic I found on a quick Google search<< ;)

 

[Silver88]

I believe it is a 1/2", a deep socket really helps if ya got one.

[mknherhappy]

Correct...that is an integral part of the pressurized system so the only fix is replacement.

 

Be sure to search a little on here for instruction on how to properly bleed the air out of the system when you change it or you will be replacing it again shortly when it overheats and blows it out. Ask me how I know... :oops: ;)

 

How do I know if I replaced the tank correctly? I do not have a temp gauge, just an idiot light.

 

Thanks again.

[88XJSport]

 

I do not have a temp gauge, just an idiot light.

 

Thanks again.

 

Temp gauge or idiot light, you still have a sender in the spot pictured.

[BLHTAZ]

The only way to be sure you have installed it correctly and have all the air out is to fire it up and drive it for just a few miles to get it up to temp. If you have air...it will start to overheat fairly quickly...or...you will notice the bottle on the firewall start to swell up a bit. If you do as instructed here though, you should be OK. ;)