Cooling system.

[tiltonb]

Am I overfilling my system.  I have a few issues since I changed my water pump.  My pickup blew a hose so I replaced it, and so it blew another.  I pulled the thermostat and filled it back up.  Today on the way home it blew another hose.  Am I over filling it?

[MJCARENA]

I don't think you can over fill a cooling system. How old are the hoses? My life experiences say, when one hose breaks, change them all, saves on coolant. Good time to change the belt also.

[tiltonb]

I did some research, it says 1.5 gallons, then add water if needed.  I'm going to try that after changing the rest of the hoses.  Thanks

[AZJeff]

4 hours ago, tiltonb said:

Am I overfilling my system.  I have a few issues since I changed my water pump.  My pickup blew a hose so I replaced it, and so it blew another.  I pulled the thermostat and filled it back up.  Today on the way home it blew another hose.  Am I over filling it?

The cooling system on the XJ and MJ vehicles are, under the best of conditions, just barely able to handle the “worst case” heat load from the engine.  It’s the Achilles Heel of the beast.  Deterioration of system parts often pushes the system into the overheating mode.

 

The older ones with “Closed” cooling system are even MORE sensitive to the deterioration issues.  If you blew one hose, it’s a good bet they are ALL in bad shape.  also, the pressure tank and it’s cap on the closed systems is prone to leaking and/or bursting with old age.

 

Finally, you say you removed the t’stat.  Was that in hopes of lowering cooling system pressures?  If so, that is NOT going to fix the issue, as the t’stat controls the MINIMUM operating temperature once warmed up,  NOT the maximum temperature.  Stick a good 195* thermostat back in the system when you replace all the hoses.
 

Lastly, what temperatures is your engine actually seeing when warmed up running at say, 30mph?

[Dammerung]

I bet your hoses are old. Check you hose clamps to make sure they are tight. Also make sure there isn’t air in your system, which may be making it act so wild. But also, maybe there is a block in the system somewhere? Try and flush the system if you can.


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[coolwind57]

One other thing to consider is that you may have a head gasket issue.  I had this symptom on a Mercedes Diesel once.  The blown gasket leaking over-pressurized the coolant system and my hoses swelled like a balloon.  Don't know for sure if this could happen on an MJ but might be worth looking in to.

[yxmj]

Just to be sure.....You replaced your water pump with one that rotates the same way?

There are reverse rotation pumps (that look and fit exactly the same).

Lack of proper circulation could cause overheating and would blow the hose....

[Eagle]

21 hours ago, MJCARENA said:

I don't think you can over fill a cooling system. How old are the hoses? My life experiences say, when one hose breaks, change them all, saves on coolant. Good time to change the belt also.

 

Yes, you can overfill a cooling system. The OP has an '89, according to his signature. The '89 has the closed cooling system. The coolant bottle on the firewall is an expansion tank. It is supposed to be filled halfway when cold -- there a tab sticking up in the middle of it that's the full indicator. Coolant expands as it heats up. With the closed system, you need the air space in that bottle to allow for expansion. If you overfill it, the pressure of expansion will cause something to let go. Usually that's the cap on the bottle, but I suppose if could be a hose.

 

Good call by yxmj, too. It's very possible that your new water pump doesn't have the correct impeller.

 

 

[MJCARENA]

3 hours ago, Eagle said:

 

Yes, you can overfill a cooling system. The OP has an '89, according to his signature. The '89 has the closed cooling system. The coolant bottle on the firewall is an expansion tank. It is supposed to be filled halfway when cold -- there a tab sticking up in the middle of it that's the full indicator. Coolant expands as it heats up. With the closed system, you need the air space in that bottle to allow for expansion. If you overfill it, the pressure of expansion will cause something to let go. Usually that's the cap on the bottle, but I suppose if could be a hose.

 

Good call by yxmj, too. It's very possible that your new water pump doesn't have the correct impeller.

 

 

I was thinking open cooling system. I converted both of my renix jeeps to open type. Expansion tank never crossed my mind.

[tiltonb]

Thank you everyone.  I replaced my radiator and the pressure bottle.  The radiator had a small leak.  It looks like it had been leaking for a while.

[tiltonb]

I also found out that you can overfill the system.  A mechanic at work told me that the best way to fill my system is to take the top radiator hose off and fill it through the hose.  Poor the antifreeze in, then add water until it flows out of the radiator neck.  That worked just fine.

[MiNi Beast]

sweetness. 

[tiltonb]

Well darn.  Still blowing hoses.  I watched some youtube videos.  One guy warned that you need to make sure that the impeller is the right one.  I guess I'll check that next.

[coolwind57]

After hearing your updates, I'm still leaning towards a head gasket issue.

[Eagle]

On 6/22/2020 at 10:25 PM, tiltonb said:

I also found out that you can overfill the system.  A mechanic at work told me that the best way to fill my system is to take the top radiator hose off and fill it through the hose.  Poor the antifreeze in, then add water until it flows out of the radiator neck.  That worked just fine.

 

What radiator neck? Your signature says your truck is an '89, and your opening post says you replaced the coolant bottle, so you must still have the coolant pressure bottle on the firewall. The radiator for the closed system doesn't have a filler neck.

 

Did you "burp" the system after filling it? The closed system is very hard to fill, and almost impossible to fill in one try when cold. What I have found works is to fill it unti the level in the pressure bottle is half full, start it up with the cap on the pressure bottle loose, and let it warm up until the coolant starts to bubble out of the bottle. BE CAREFUL -- it's hot enough to scald you.

 

As soon as it starts to bubble, shut off the engine. Remove the cap from the bottle. Wait while it cools down. In a couple of minutes it will start sucking coolant back out of the bottle -- when that starts to happen, add coolant to replace what's being sucked out, keeping the level in the bottle at least to the halfway point. When it stops sucking, start it up and repeat. You may have to do this three or more cycles to "burp" all the air out of the system.

 

 

[JustEmptyEveryPocket]

To add to Eagle's post: remove the temperature sender at the back of the head during your first cold fillup. This will let air escape easier. Just be ready to cram it back in in a hurry as you watch your precious coolant flow out the tiny hole and down the block.

[tiltonb]

It is the head gasket.  Mr Eagle, yes it is the closed system.  I had burped it, but that doesn't help when the head gasket is blown.

[tiltonb]

Oh, I'm going with the good old radiator with a neck.  I am removing the pressure bottle and replacing that with an overflow bottle.

[Eagle]

56 minutes ago, tiltonb said:

Oh, I'm going with the good old radiator with a neck.  I am removing the pressure bottle and replacing that with an overflow bottle.

 

Be sure the radiator you get has a place to install the temp switch for the auxiliary fan. If you have an aux fan, the switch is mounted about halfway down in the driver's side radiator tank. Most of the radiators with a neck don't have that bung, because the HO system controls the aux fan through the PCM.

[silvertwinkiehobo]

If you go to your friendly neighborhood parts store, you can get a later-model XJ rad, aluminum with plastic tanks, and it'll definitely have the bung down below. Thank you, whomever decided to carry fewer SKU's.