258 problems - Off-Road Forums & Discussion Groups
Jeep-Short Wheelbase All discussion of short wheelbase Jeeps: CJ, TJ, YJ and JK

 
LinkBack Thread Tools Display Modes
post #1 of (permalink) Old 10-13-2000, 09:48 PM
**DONOTDELETE**
Guest
 
Posts: n/a
258 problems

I have a 1978 cj5 with a 258 that I just rebuilt.My timing and idle speed are probably not right on the money,but my temp. gauge is pegging out on the hot side.Also the lower radiater hose is cool, while the top is hot.Radiator has been flow tested and cleaned,new water pump,new thermostat,new hoses.Also ,the radiator cap has no pressure on it after some fairly long idle time.

TOMMY PARKER
Sponsored Links
Advertisement
 
post #2 of (permalink) Old 10-13-2000, 10:16 PM
 
Join Date: Sep 1999
Posts: 5,383
Thanks: 0
Thanked 1 Time in 1 Post
 
Re: 258 problems

Thermostat is bad or installed upside down more than likely.

You may also have a bad water pump.
-------------------------------------


Take the top radiator hose off the radiator. Let the hose hang.
Stick the garden hose in the radiator.
Start the vehicle, and let it warm up.
If the thermostat opens, hot water will gush out of the top hose, so be careful.
If the water gushes, the system is working correctly for the most part.
-----------------------------

Check your gauge by putting everything together, and putting a cheap cooking thermometer in the radiator.
Leave the cap off, make sure the system is full, and start the vehicle and let it warm up.
See if the thermometer and the gauge agree when the thermostat opens...
------------------------------

If the thermostat doesn't open, the hot water will just trickle out of the loose radiator hose.
Now it's time to check your thermostat.

Take the thermostat out of it's housing.
Make sure it's installed correctly. The larger part of the thermostat should be in the engine.
If it was installed correctly, throw it in a pan of water with a cheap cooking thermometer, and set the pan on heat on the stove.
Pay attention to see when it opens. It moves internally, and compresses the spring.
Check the thermometer to see what temp the water is... That will verify the thermometer.
-----------------------------

If the thermometer and gauge check out, Then it's off the water pump ...
First off, check to see the water pump is turning the correct direction, and it has the 'by pass' hose not kinked.

If you put the water neck back on the engine, WITHOUT the thermostat installed.
Don't worry about the gasket, just screw it down. This is a test, and you have to put a thermostat back in, so let it leak for now.

Hook the radiator hose up to the thermostat housing, and take the hose loose from the radiator.
Fill the radiator up, and start the engine.
The water should 'gush' out right away with not thermostat in place, and a water pump working correctly.

If the water doesn't 'gush' out, you have a bad water pump, or internal restrictions in the block, radiator or hoses.
------------------------------

If everything checks out, but it's still overheating, check to see if you have the correct pulleys on the pump and crankshaft.
If you mixed up pulleys, you may not be turning the pump at the correct speed to keep the engine cool.

Contrary to popular belief, it's just as easy to turn the pump too fast as it is too slow.
-----------------------------

If this doesn't help, get back with us and we'll try some more things...


"I Have The Body Of A God... Buddha"
Junk Yard Genius is offline  
post #3 of (permalink) Old 10-13-2000, 11:16 PM
**DONOTDELETE**
Guest
 
Posts: n/a
Re: 258 problems

When I put on the new waterpump,the old fan pulley hit the pump.I changed out pulley's and never thought about them being differant sizes.I did not look, because I did not know!

TOMMY PARKER
Sponsored Links
Advertisement
 
post #4 of (permalink) Old 10-14-2000, 08:26 AM
Keyboard Implanted
 
jeepgod's Avatar
 
Join Date: Jan 2000
Location: Wildomar, CA
Posts: 4,618
Thanks: 0
Thanked 3 Times in 3 Posts
 
Re: 258 problems

cjtom.. here is a problem i ran into.. some of those water pumps you get from the auto stores.. are not all the same.. some have the fins going the opposite direction.. so it will be spinning but ineffectively.. i changed it out.. and then with the second pump.. my pulley hit the casing of that one.. so i took it back..
do you have your oringinal pump? if you do take it with you.. but definetly get a new pump.. so the correct pulley fits on it.. all those output shafts are not the same length

<font color=orange>survival is instinct, but living takes guts</font color=orange>

http://www.jeepgod.net
jeepgod is offline  
post #5 of (permalink) Old 10-14-2000, 09:36 AM
 
Join Date: Sep 1999
Posts: 534
Thanks: 0
Thanked 0 Times in 0 Posts
 
Re: 258 problems

TR was right on with all cooling system checks...just thought I'd add a note about the depth of pulleys on the 258
waterpumps...All 258's use the same cast waterpump. AMC cars however use different pulleys. The flange on
AMC cars is closer to the pump. So, if a parts store has given you the AMC car pump your pulley will hit the
cast. Just a FYI. For some reason the computers we use at work list both pumps when you look it up for a
258. Yes, I know you should use the book! And I like the books very much!

Alec

'78 CJ7 258 T18/dana 20 dana 30/amc 20 w/ mosers & lockrights
'glass body tied in full cage

http://members.aol.com/fastflyn31/page1.html
Alec78CJ is offline  
post #6 of (permalink) Old 10-14-2000, 09:53 AM
 
Join Date: Sep 1999
Posts: 5,383
Thanks: 0
Thanked 1 Time in 1 Post
 
Re: 258 problems

Way to go Alec, you stumped me with that one.
I had no idea about the different water pump lengths on AMC I-6 engines.
Looks like you are coming around.... Starting to build a good knowledge base....
Good work!
---------------------------------

DON'T worry about the pulley just yet...
If it's turning the pump, the top radiator hose should be hot, and so should the bottom radiator hose, and you said it's not....
SO....

The only conclusion is that the water flow is restricted by the thermostat or by the radiator, or the wrong head gasket or improperly installed head gasket restricting flow....

Do the tests I laid out for you. It will only cost you a thermostat housing gasket and a $4 cooking thermometer to do the tests, and you will know for sure....

DON'T GUESS DO THE TESTS VERIFY FUNCTION

"I Have The Body Of A God... Buddha"
Junk Yard Genius is offline  
post #7 of (permalink) Old 10-14-2000, 11:19 PM
**DONOTDELETE**
Guest
 
Posts: n/a
Re: 258 problems

Had A few moments after work to tinker with the 258.Tomorrow I will do the test as outlined by TEAMRUSH.In the meantime,I had made a little adjustment on the idle speed,and the bottom hose started to warm up.I squeezed the bottom hose and felt a surge of coolant.By the way, it's hard to squeeze a hose that has a wire coil in it and feel anything.Could I have not set idle speed high enough to turn the pump fast enough to turn the pump the correct speed?

TOMMY PARKER
post #8 of (permalink) Old 10-15-2000, 09:10 AM
Keyboard Implanted
 
jeepgod's Avatar
 
Join Date: Jan 2000
Location: Wildomar, CA
Posts: 4,618
Thanks: 0
Thanked 3 Times in 3 Posts
 
Re: 258 problems

thanks alec.. always wondered why that had happened..
do you know the years where they changed the fins.. ? im glad i didnt install that one.. or would have been really p.o'd..

<font color=orange>survival is instinct, but living takes guts</font color=orange>

http://www.jeepgod.net
jeepgod is offline  
post #9 of (permalink) Old 10-15-2000, 09:57 AM
Can't Get Enough
 
Join Date: Sep 1999
Location: Cotopaxi, Colorado
Posts: 1,036
Thanks: 0
Thanked 0 Times in 0 Posts
 
Re: 258 problems

Alec78cj is incorrect, there are two different water pumps for the 258. The one for the serpentine belt turns in a different direction, like the 4.0's. I would follow Jeepgod's advise, and pull the pump, and verify that the parts store gave you the proper pump. I have ran into this more that once.

dorfs is offline  
post #10 of (permalink) Old 10-15-2000, 03:42 PM
 
Join Date: Sep 1999
Posts: 534
Thanks: 0
Thanked 0 Times in 0 Posts
 
Re: 258 problems

Sorry I didn't think about the reverse rotation on later serpentine models...either way the casting of the pump is still the same.
Hope I didn't cause any confusion.

Alec

'78 CJ7 258 T18/dana 20 dana 30/amc 20 w/ mosers & lockrights
'glass body tied in full cage

http://members.aol.com/fastflyn31/page1.html
Alec78CJ is offline  
Sponsored Links
Advertisement
 
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Off-Road Forums & Discussion Groups 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 email address for yourself.

Email Address:
OR

Log-in










Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode



Posting Rules  
You may not post new threads
You may not 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 On
Pingbacks are On
Refbacks are On

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