overheating help

zrtwooo · **Posted:** Tue Jan 06, 2009 1:06 am

ok so now i'm a bit confused...
1. the f37 might have been done back when i got the lbj replaced and something to reduce the torque in the trans... anyone know when that started to be done?
2. I need a egr valve per power dodge up on bell but i bought one and thought i wanted to put it in myself, but i came to my senses. do i need to have it replaced if #3's ans is no and yes respectively
3. does the egr block off send a cel? does this do the same thing as thr segr?
4. can the temp gauge be fixed without getting the f37?
5. if it cools down as soon as the load is removed how can you put your gizmos on it TurboTim?
6. do i understand you guys to be saying the fan clutch not working can be this elusive in normal city-no trailer-highway speed driving but only show its not working properly in a sustained-highway speed load?
FSHEW!
thx
Mike

nursecosmo · **Posted:** Tue Jan 06, 2009 2:16 am

zrtwooo wrote:

1. the f37 might have been done back when i got the lbj replaced and something to reduce the torque in the trans... anyone know when that started to be done?

The "something to reduce torque" IS the F37 reflash.

zrtwooo wrote:

2. I need a egr valve per power dodge up on bell but i bought one and thought i wanted to put it in myself, but i came to my senses. do i need to have it replaced if #3's ans is no and yes respectively

If you remove it and clean the valve portion with parts cleaner it will probably be sufficient to get it moving freely again.

zrtwooo wrote:

3. does the egr block off send a cel? does this do the same thing as thr segr?

Yes it throws a CEL. No it is not the same as the SEGR install but the effect is the same.

zrtwooo wrote:

4. can the temp gauge be fixed without getting the f37?

No. When any jeep is brought in for any reflash, the star computer automatically installs the latest flash which includes all of the revisions up to that date.

zrtwooo wrote:

6. do i understand you guys to be saying the fan clutch not working can be this elusive in normal city-no trailer-highway speed driving but only show its not working properly in a sustained-highway speed load?

Yes. Faulty fan clutches can sometimes work intermittently when the mechanism gets sticky or bi-metal springs get weak. Sometimes there is no identifiable cause. Sometimes a long, hot, high RPM run will loosen things up and make it work again.

Sometimes they are not the cause of the overheating problem at all, but are one of the things to consider as the cause.

Another thought which struck me in the side of the head is the possibility of the viscous coolant engaging at inappropriate times, but this is a highly unlikely event.

Ranger1 · **Joined:** Mon Oct 17, 2005 7:40 pm **Posts:** 1137

Quote:

3. does the egr block off send a cel? does this do the same thing as thr segr?

An egr blocking plate is nothing more than a piece of metal(which you have to fabricate yourself), shaped like the exhaust flange on the egr valve, which prevents exhaust gas flow into the egr, egr cooler and intake manifold of the engine. In itself, it has no ability to generate any CEL/MIL(same light, different names in this discussion). If a blocking plate is installed, when the engine computer commands egr/afc action to occur, it will watch for a corresponding reduction in MAF flow. If it doesn't see it on US models, it will set a CEL/MIL light on your dash and store some OBD codes.

The blockoff plate and segr are entirely different animals. A blockoff plate stops exhaust flow into the egr, nothing more. A segr sits electronically between the engine computer and the egr/afc/maf devices. It prevents the egr from opening the valve and prevents a CEL by telling the engine computer what it wants to see. It can't fix a stuck egr valve in the open position, hence the blockoff plate requirement if you can't repair or replace the egr.

zrtwooo · **Posted:** Tue Jan 06, 2009 9:35 am

Ok so I'm taking it to the stealership to get the egr replaced, and then check the fan. By the way, how can i check to be sure the fan clutch is or isn't working properly? I think i already have the f37 I'll ask to get the current tsb's fixed. (ie temp gauge).. does anyone know how much the segr is running these days? and at 67k it wont hurt to replace a radiator cap.
thanks for all the help!
Mike

danoid · **Posted:** Tue Jan 06, 2009 9:46 am

Don't forget we have two fans for cooling. A low power electric for low speed (primarily helps the air conditioning) and the main viscous clutched fan. I've never had my dash gauge 'recalibrated' and when I'm towing it generally is 3/4 to 7/8 over to the right. It's not a problem, the recalibration only made the gauge lie more.

Towing is the only time I notice my viscous clutch engage, and at 2200 engine rpm, you'll hear it. It will kick on about 220° coolant temp and force things down to about 212°. I don't believe it will engage at much over 2500 engine rpm however, so if you are in third gear at 3000+ rpm your cooling capacity is actually less.

In the end, if coolant temps get past 235°(ish) you'll hear a chime. Keep pushing it and you'll start to lose power as the engine reduces fuel to reduce heat.

PhoenixCRD · **Posted:** Tue Jan 06, 2009 12:02 pm

zrtwooo wrote:

ok so now i'm a bit confused...
2. I need a egr valve per power dodge up on bell
Mike

I would not take my CRD to Power Dodge as they didn't sell any CRD's (salesmen (plural) didn't know they existed when I looked for mine). Their mechanics probably didn't even get to see the 10 minute CRD repair video. JMO of course

zrtwooo · **Posted:** Tue Jan 06, 2009 12:35 pm

Yes Gary I completely agree they are a bunch of money grubbing doushebags that don't really seem to want to deliver any quality standard of customer service. I won't ever go back there!!! I dropped the lil big rig off this am and to my suprise the TSB's are not covered under any factory recall or warr program. I,if I wanted it, would have to pay to fix their mess up? good ole DC!!
That info is good to know Danoid. I opted not to pay for the reflash.
how can I check to be sure the fan clutch is or isn't working properly? Is towing with it at those rpm ranges stated the only way?
thx
Mike

nursecosmo · **Posted:** Tue Jan 06, 2009 4:43 pm

zrtwooo wrote:

Yes Gary I completely agree they are a bunch of money grubbing doushebags that don't really seem to want to deliver any quality standard of customer service. I won't ever go back there!!! I dropped the lil big rig off this am and to my suprise the TSB's are not covered under any factory recall or warr program. I,if I wanted it, would have to pay to fix their mess up? good ole DC!!
That info is good to know Danoid. I opted not to pay for the reflash.
how can I check to be sure the fan clutch is or isn't working properly? Is towing with it at those rpm ranges stated the only way?
thx
Mike

Have you read KeighJeigh's thread about his problems with overheating?
http://www.lostjeeps.com/forum/phpBB3/vie ... &start=100
I can't remember whether he had overheating at highway speeds or not. Maybe you could PM him.

danoid · **Posted:** Tue Jan 06, 2009 10:08 pm

zrtwooo wrote:

how can I check to be sure the fan clutch is or isn't working properly?

Well, there are a few other ways...

KJ service manual wrote:

DIAGNOSIS AND TESTING
If the fan assembly free-wheels without drag (the fan blades will revolve more than five turns when spun by hand), replace the fan drive. This spin test must be performed when the engine is cool.

For the following test, the cooling system must be in good condition. It also will ensure against excessively high coolant temperature.

WARNING: Be sure that there is adequate fan blade clearance before drilling.

Drill a 3.18-mm (1/8-in) diameter hole in the top center of the fan shroud.
Obtain a dial thermometer with an 8 inch stem (or equivalent). It should have a range of -18° to 105°C (0° to 220° F). Insert thermometer through the hole in the shroud. Be sure that there is adequate clearance from the fan blades.
Connect a tachometer and an engine ignition timing light (timing light is to be used as a strobe light).
Block the air flow through the radiator. Secure a sheet of plastic in front of the radiator (or air conditioner condenser). Use tape at the top to secure the plastic and be sure that the air flow is blocked.
Be sure that the air conditioner (if equipped) is turned off.
WARNING: Use extreme caution when the engine is operating. Do not stand in a direct line with the fan. Do not put your hands near the pulleys, belts or fan. Do not wear loose clothing.

Start the engine and operate at 2400 RPM. Within ten minutes the air temperature (indicated on the dial thermometer) should be up to 93° C (200° F). Fan drive engagement should have started to occur at between 91° to 96° C (195° to 205° F). Engagement is distinguishable by a definite increase in fan flow noise (roaring). The timing light also will indicate an increase in the speed of the fan.
When the air temperature reaches 93° C (200° F), remove the plastic sheet. Fan drive disengagement should have started to occur at between 62° to 85° C (145° to 185° F). A definite decrease of fan flow noise (roaring) should be noticed. If not, replace the defective viscous fan drive unit

nursecosmo · **Posted:** Tue Jan 06, 2009 10:37 pm

Alternatively there is the "string test". Acquire a length of Manila or Sisal twine. Start the engine for a minute or two to loosen up the fan clutch, but do not allow the vehicle to get warmed up, then turn off. Now tie one end of the string to one of the fan blades and the other end to some point in the engine bay. Next block off radiator air flow with some plastic, cardboard, etc... Start the engine. The string should be strong enough to hold the fan without breaking at ~1000 RPM or so. Monitor the temperature per the above posted KJ manual instructions or even better yet with an infrared thermometer. as the temperature approaches the clutch engagement point the string should break.

This method is a very brute force approach and not very accurate. It can identify a very badly failing clutch but probably not a borderline one.

The above posted method only works on a Gas vehicle seeing as how we do not have any plug wires to tap a timing light into. Of course one could always park another vehicle next to the CRD and run the timing light off of that one.

DO NOT STAND CLOSE TO THE FAN WHEN DOING THIS PROCEDURE

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