Engine Woes – Walked home.

[NC Tom]

For the past few weeks I've had steam and fluid spouting from the plastic bottle on my 88 4.0 Renix. That has been the only issue that some thang won't raght.

 

Friday, engine was slow to start, but otherwise the same. End of day, again, slow to start but this time, by the time I had driven less than two miles, I had lots of steam! Idiot light never came on. Turned truck off, opened hood and had steam all around. Prior to this I had found a crack in the plastic bottle. I replaced that today, added FSM level of coolant, checked oil. It's dirty, but does not look like a milkshake. Started truck, slow to start, ran fine for about 3 minutes. Idle started creeping up and creeping up and creeping up. I decided to drive a bit. Idle dropped after shifting into reverse. It's an auto.

Drove maybe a mile, shut off, steam everywhere again. Would not start, but would slowly turn over. Walked home. Let it cool for a while, was able to start it and get it back home. So, the video is shortly after I pulled over. I'll likely be getting it towed to the dealer unless you smart folks have any idea what's happening. I'd rather not go to the dealer, but I've been going to local mechs and I'm not sure they know what they are doing. Thinking the dealer would be better, albeit, more expensive. Oh, it's been a bit cooler here if that matters. The battery is dated 2015 and could be the source of the slow start.

 

 

[omega_rugal]

you have a small coolant leak somewhere...

[Jeep Driver]

Would like to have heard it running or you trying to start it. 

 

Condensation in the dist cap will cause slow start and rough run. 

[cruiser54]

Using a cheapie chinese coolant bottle cap?

If it came off the old bottle, it is surely toast and not holding pressure.

Get a 703-1396 cap from Napa or an equivalent. From a Volvo. 

Check the dizzy cap as Jeep Driver suggests also.. 

[NC Tom]

8 hours ago, cruiser54 said:

Using a cheapie chinese coolant bottle cap?

If it came off the old bottle, it is surely toast and not holding pressure.

Get a 703-1396 cap from Napa or an equivalent. From a Volvo. 

Check the dizzy cap as Jeep Driver suggests also.. 

 

Right. I have to order that cap, but I was concerned that it could be something worse. Based on the video and my "story" you think the system is not holding pressure? Nothing more?

I'm wondering if I don't have enough coolant flowing through. Problem is, I've read many of the "MJ overheating" posts and I still don't understand how to tell how much coolant I have/need or even how to add it to a closed system.

 

Actually, I know how to add coolant to the plastic bottle up to the small pipe, but other than that, I'm not sure how to tell how much more may be needed.

[omega_rugal]

Just now, NC Tom said:

Based on the video and my "story" you think the system is not holding pressure? Nothing more?

 

if the system can not build pressure it will overheat, sounds stupid but that´s how it goes...

[Wounded_Fighter]

Was that engine oil on the ground off the front of the block?? Wheres that coming from??

 

[NC Tom]

50 minutes ago, omega_rugal said:

 

if the system can not build pressure it will overheat, sounds stupid but that´s how it goes...

I figured that. Why I was wondering about proper filing and knowing when it's full.

[NC Tom]

31 minutes ago, Wounded_Fighter said:

Was that engine oil on the ground off the front of the block?? Wheres that coming from??

 

Coolant.

[cruiser54]

Get the cap...

 

 

[johnj92131]

Tom,

 

A couple of years back when I was refilling my cooling system, I forgot to open the heater.  Net result - I never got the cooling system properly filled.  So my over heating problems did not go away till somebody showed me I need to run the heater.  That never crossed my mind in San Diego.

[rokinn]

In addition to the cap make sure the air is being properly purged from the system.  Also check to make sure the O rings on the radiator are not leaking, even a little bit.  You can lose pressure from there over time also.  Make sure all of the hoses are tight.

[HOrnbrod]

3 hours ago, johnj92131 said:

Tom,

 

A couple of years back when I was refilling my cooling system, I forgot to open the heater.  Net result - I never got the cooling system properly filled.  So my over heating problems did not go away till somebody showed me I need to run the heater.  That never crossed my mind in San Diego.

 

If you ditched of that POS water control valve you would never have that problem again. It creates trapped air pockets in the system. 

[WahooSteeler]

4 hours ago, cruiser54 said:

Get the cap...

 

 

Cruiser, I'm assuming those are hot and cold level markings? Picture won't zoom for me to read. 

[NC Tom]

On 8/28/2018 at 8:53 AM, cruiser54 said:

Get the cap...

 

 

 

Okay, okay . . . I got the cap!

 

Marked the levels as you did, filled it up, charged battery, started truck, slow idle builds to very fast idle, got nervous, shut if off after 5-7 min or so, coolant in expansion tank did not get sucked in. Also, I just remembered I did not turn on the heater. However, I'm thinking maybe the temp sensor is bad. I know it should be easy, but I CANNOT find the bastard. It's a Renix 4.0. All the diagrams I see make my brain hurt. All the photos I see are not Renix since the sensor is right there on top in a convenient location.

 

To find the sensor, should I be under the truck looking up?

 

I'll turn the heater on and report back.

[NC Tom]

Alright, maybe I'm getting somewhere now.

 

Switched over to heat, started up, idle rose very high again, put it in gear idle calmed down. The idle only increases while in Park. Ran it for a bit, turned it off, heard steam, bottle was empty and about to pop.

 

So, Chiltons says to do this procedure until the bottle does not suck all the fluid out. I guess that's my plan for today unless someone here has a better idea.

 

 

[rokinn]

By all indications you are not getting the system purged.  When I first got my MJ one of the first things I had to do was replace the radiator after it sprang a leak.  I had the same problems with overheating after that until I learned how to purge the air from the system.  Here's what I did.  I took out the water control valve and ran hoses directly in and out of the heater (optional).  I installed a 91+ thermostat housing with a brass plug (NPT) where the temp sensor goes and put in an OEM thermostat with the hole oriented up.  If you want to use an aftermarket stat drill a 3/16" hole in it and orient it up.  This will allow air to pass through it.  The engine should be cold to purge the air from the system.  Fill the bottle to the half way line with coolant and leave the cap off.  Take the plug out of the Tstat housing and wait for coolant to start coming out of the hole and then reinstall the plug.  Fill the bottle to the half way line and put the cap back on.  It shouldn't over heat now (unless something else is wrong).  The other way to purge the air is to remove the temp sensor at the back of the head (cold engine) (MJ nose pointed down hill preferably) and wait for coolant to start to come out.  The other way sets you up for easy purging should it need it again anytime in the future.  Good luck.

[cruiser54]

Replace the cap with the Volvo one.

 

Here's the temp sender for ya. 

 

 

[NC Tom]

2 hours ago, cruiser54 said:

Replace the cap with the Volvo one.

 

Here's the temp sender for ya. 

 

 

Yes, I have the cap.

 

Here's where I'm at after lots and lots of reading.

Removed exp tank cap

Added coolant, left cap off

Started, let run

After coolant began to get suck in, I slowly added more

Was running good. Next thing you know, coolant was bubbling up out of the exp bottle all over the place!

Leveled out, still ran fine, coolant in exp bottle was lower and seemed stable

Turned off truck, exp bottled almost emptied when sucked in again

 

I imagine everything that happened was normal. I think I lost a whole bottle of coolant during the bubbling part though.

From here, I guess I need to add coolant back to the MAX line, put the cap back on and let her run a bit, and expect nothing abnormal to happen?

Also, the climbing idle didn't happen this time. I guess it was related to the low coolant.

 

[NC Tom]

So far, so go on this adventure! Thanks for all the feedback! 

[cruiser54]

It's good?

[Eagle]

On 8/27/2018 at 7:26 PM, NC Tom said:

I figured that. Why I was wondering about proper filing and knowing when it's full.

 

You fill it to the half-full mark when it's cold, then you start it up and "burp" it. Leave the cap loose, start it, and let it run until it gets hot enough to start boiling. As soon as you see bubbles ... shut it off. Remove the cap (carefully, using long pliers or something). Watch until the coolant starts to suck down, then add slowly, to keep the level at the half-full mark. Once it stops sucking, start it up and repeat until no more air bubbles come out.

 

Usually a couple or three cycles will get it driveable. After that, just check it before every cold start for a couple of days until you don't need to add any more. Sounds like you pretty much got it figured out.

[HOrnbrod]

Closed systems.  

[NC Tom]

On 9/3/2018 at 12:13 AM, Eagle said:

 

You fill it to the half-full mark when it's cold, then you start it up and "burp" it. Leave the cap loose, start it, and let it run until it gets hot enough to start boiling. As soon as you see bubbles ... shut it off. Remove the cap (carefully, using long pliers or something). Watch until the coolant starts to suck down, then add slowly, to keep the level at the half-full mark. Once it stops sucking, start it up and repeat until no more air bubbles come out.

 

Usually a couple or three cycles will get it driveable. After that, just check it before every cold start for a couple of days until you don't need to add any more. Sounds like you pretty much got it figured out.

 

Thanks, Eagle. Yes, she's running much better now! Seems like there is a few options on your solution above. The one I chose was a bit messy, but it's all good!