4.7 HO overheating and rough idle - Page 2 - JeepForum.com

Reply
 
LinkBack Thread Tools
post #16 of 38 Old 09-02-2014, 04:38 AM
86cj74.2L
Web Wheeler
 
86cj74.2L's Avatar
2004 WJ 
 
Join Date: Jul 2006
Location: Stouchsburg, PA
Posts: 10,175
Quote:
Originally Posted by Knoxes
I rebuilt the top end. Had the heads decked .010, basic valve job, new gaskets, new water pump, some hoses, belt, etc. It's running fine, but seems to be running just a bit hot - hasn't really gotten over the 210 mark (maybe slightly), and seems to hold there even when left idling for some time. On the freeway, it's solidly below 210 - probably right on the 195 mark for the thermostat. But I'm not entirely sure that it's cooling properly. After the initial 2 hour drive home from the rebuild, it seems to have taken a bit more coolant from the reservoir. Concerned that I still have some problems here.
It will take about three drive cycles to stop pulling coolant from the tank.

Both my and Grammys 2004 4.7's run at or just below 210. Always........winter and summer. Driving or idling.

86cj74.2L is offline  
Sponsored Links
Advertisement
 
post #17 of 38 Old 09-02-2014, 07:02 AM Thread Starter
Knoxes
Registered User
 
Knoxes's Avatar
2011 WK 
 
Join Date: Feb 2004
Posts: 378
Good to know.

I just don't recall what temp it ran at prior to this. Should post a poll...
Knoxes is offline  
post #18 of 38 Old 09-02-2014, 08:01 AM
86cj74.2L
Web Wheeler
 
86cj74.2L's Avatar
2004 WJ 
 
Join Date: Jul 2006
Location: Stouchsburg, PA
Posts: 10,175
Quote:
Originally Posted by Knoxes
Good to know. I just don't recall what temp it ran at prior to this. Should post a poll...
You only start to OT attention to something after the fact. Its human nature.

Do some spirited acceleration to push any air trapped in the heater core to the rad. You may hear the air in the glove box sound for a little while till its all away.
86cj74.2L is offline  
post #19 of 38 Old 12-10-2014, 08:50 AM Thread Starter
Knoxes
Registered User
 
Knoxes's Avatar
2011 WK 
 
Join Date: Feb 2004
Posts: 378
I've put about 3k miles on it since completing the head gasket job, including some long, heavier load trailer tows. Recently, it's back to (sometimes) idling around 500 in gear, which is kind of low and rough, and it might be losing some coolant. I haven't confirmed the coolant level yet, but I'm pretty sure. It's also gurgling in the heater core and might be blowing some white smoke/steam, but I'm not sure about that. The weather here turned a month ago, so cold and wet = some visible exhaust. No sign of foaming in the oil.

Bottom line - it's doing everything that it was before EXCEPT overheat. My machine shop tells me that it can't be the head gasket if it isn't overheating. But I tested the coolant for exhaust gas last weekend and got a negative reading. Not sure what to do next?
Knoxes is offline  
post #20 of 38 Old 12-10-2014, 09:50 AM
86cj74.2L
Web Wheeler
 
86cj74.2L's Avatar
2004 WJ 
 
Join Date: Jul 2006
Location: Stouchsburg, PA
Posts: 10,175
Quote:
Originally Posted by Knoxes
I've put about 3k miles on it since completing the head gasket job, including some long, heavier load trailer tows. Recently, it's back to (sometimes) idling around 500 in gear, which is kind of low and rough, and it might be losing some coolant. I haven't confirmed the coolant level yet, but I'm pretty sure. It's also gurgling in the heater core and might be blowing some white smoke/steam, but I'm not sure about that. The weather here turned a month ago, so cold and wet = some visible exhaust. No sign of foaming in the oil. Bottom line - it's doing everything that it was before EXCEPT overheat. My machine shop tells me that it can't be the head gasket if it isn't overheating. But I tested the coolant for exhaust gas last weekend and got a negative reading. Not sure what to do next?
500rpm in gear is normal for the 4.7. The ruff idle can easily be uneven flowing injectors. When the head was replaced a lot of coolant drained out of block and heater core. The gurgling is just the air pocket. Doing some spirited acceleration should push the air to the rad. Where the vent valve in the rad cap can let it vent to the overflow tank.
86cj74.2L is offline  
post #21 of 38 Old 12-10-2014, 09:57 AM Thread Starter
Knoxes
Registered User
 
Knoxes's Avatar
2011 WK 
 
Join Date: Feb 2004
Posts: 378
Sure, but after 3K miles and 3+ months of driving? Seems like any air pockets should have been sorted out by now.
Knoxes is offline  
post #22 of 38 Old 12-10-2014, 10:06 AM
Cavadus
Registered User
2004 WJ 
 
Join Date: Apr 2014
Location: Saint Paul
Posts: 138
Bad head, dude. Just got the diagnosis yesterday. Same exact situation, same behavior. Hope ya got some $$$ saved up. I'm going back and forth between replacing the heads or the engine as the cost will be about the same.
Cavadus is offline  
post #23 of 38 Old 12-10-2014, 10:12 AM
86cj74.2L
Web Wheeler
 
86cj74.2L's Avatar
2004 WJ 
 
Join Date: Jul 2006
Location: Stouchsburg, PA
Posts: 10,175
Quote:
Originally Posted by Knoxes
Sure, but after 3K miles and 3+ months of driving? Seems like any air pockets should have been sorted out by now.
Was it the first spirited driving? I did a drain of the coolant on my 04 for a flush and had air for a little. I drove it to work and did a bunch of fun 3/4 throttle accelerations pulling on to roads and no more air noise in the glove box.

If your rad caps vent valve is not operating properly the air will stay trapped in the top of rad. But the air should not make it back into the block.
86cj74.2L is offline  
post #24 of 38 Old 12-10-2014, 10:20 AM
86cj74.2L
Web Wheeler
 
86cj74.2L's Avatar
2004 WJ 
 
Join Date: Jul 2006
Location: Stouchsburg, PA
Posts: 10,175
Also there is a hole lot of water produced as a product of combustion. Anywhere from 7lbs of water for every gallon of gas to 1.5 gal of water per gallon of gas depending on which math you use. There is always going to be water vapor coming out tail pipe. Sometimes you see it sometimes you don't.

My and Grammies 04 4.7 always idles down to 500 in gear without AC on and idles smooth as butter.
86cj74.2L is offline  
post #25 of 38 Old 12-10-2014, 12:04 PM Thread Starter
Knoxes
Registered User
 
Knoxes's Avatar
2011 WK 
 
Join Date: Feb 2004
Posts: 378
Quote:
Originally Posted by Cavadus View Post
Bad head, dude. Just got the diagnosis yesterday. Same exact situation, same behavior. Hope ya got some $$$ saved up. I'm going back and forth between replacing the heads or the engine as the cost will be about the same.
Did you overheat after the heads were done?
Knoxes is offline  
post #26 of 38 Old 12-10-2014, 01:27 PM
Cavadus
Registered User
2004 WJ 
 
Join Date: Apr 2014
Location: Saint Paul
Posts: 138
Quote:
Originally Posted by Knoxes View Post
Did you overheat after the heads were done?
Haven't gotten that far yet. The heads just got pulled off and diagnosed yesterday. I'm currently tracking down a local shop to get them remanned at.

But if this doesn't fix it I'm probably going to drop it in Lake Superior TBPFH.
Cavadus is offline  
post #27 of 38 Old 12-11-2014, 06:56 AM Thread Starter
Knoxes
Registered User
 
Knoxes's Avatar
2011 WK 
 
Join Date: Feb 2004
Posts: 378
Wondering why the fumes test turned up negative.
Knoxes is offline  
post #28 of 38 Old 12-11-2014, 06:58 AM
86cj74.2L
Web Wheeler
 
86cj74.2L's Avatar
2004 WJ 
 
Join Date: Jul 2006
Location: Stouchsburg, PA
Posts: 10,175
Quote:
Originally Posted by Knoxes
Wondering why the fumes test turned up negative.
referring to you? I don't think it's a head gasket failure.
86cj74.2L is offline  
post #29 of 38 Old 12-11-2014, 07:54 AM Thread Starter
Knoxes
Registered User
 
Knoxes's Avatar
2011 WK 
 
Join Date: Feb 2004
Posts: 378
Quote:
Originally Posted by 86cj74.2L View Post
referring to you? I don't think it's a head gasket failure.
You might be right. But in the 3 months since the rebuild, I've certainly had my foot buried in it more than once. It's done some heavy duty in that time too.

I can hear the heater core every time I start it now.

I've been using it as my commuter this week (70 miles round trip). I'll check the coolant level tonight and see it there's any change.
Knoxes is offline  
post #30 of 38 Old 12-11-2014, 08:31 AM
86cj74.2L
Web Wheeler
 
86cj74.2L's Avatar
2004 WJ 
 
Join Date: Jul 2006
Location: Stouchsburg, PA
Posts: 10,175
Quote:
Originally Posted by Knoxes
You might be right. But in the 3 months since the rebuild, I've certainly had my foot buried in it more than once. It's done some heavy duty in that time too. I can hear the heater core every time I start it now. I've been using it as my commuter this week (70 miles round trip). I'll check the coolant level tonight and see it there's any change.
Does the coolant level rise and fall in the expansion tank like it should.

Take your rad cap off and spray it real good with brake cleaner and wiggle the vent valve in the center of the cap. It should be loose with a cold cap. Make sure your hose between the rad and tank it tight fitting. The vent valve in the cap and the tight fitting hose to the tank is how the air gets out of the cooling system.
86cj74.2L is offline  
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the JeepForum.com forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid e-mail address for yourself.



Email Address:
OR

Log-in









Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.




Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page



Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome