AMC 401 overheating

Post your Jeep related Tech here.

Moderators: Toyman1994, TallGuy, Tice, Ashman

AMC 401 overheating

Unread postby 1tonCJ » Sat Sep 12, 2009 12:00 am

Well, I went from one problem to a new one. After swapping the 401 in place of the 304, I am now having overheating issues. Here is the story.
I pulled the 304, swapped in the 401. I replaced all the gaskets on the 401, put in new plugs, new water pump, new thermistat 160 degree. and a heavy duty flex fan from Lopers. The radiator is the stock style Cj rad. but it is the 4 core heatbuster from Autozone, Could this be my problem or do I need to look somewhere else? Also, for you guys running a 401, what do you have it timed at? Mine is at 12 degrees and seems to run ok. Could the timing be causing the overheating? Any help would be nice,
-John C.
Tubed out CJ7, AMC 401, TH400 reverse manual valve body,Dana 300, 14 Bolt Rear, 60 Front, 47" LTB's, Hydro Steering
Its a work in progress, I just can't seem to progress!!
Just Empty Every Pocket
User avatar
1tonCJ
Mud Terrains
Mud Terrains
 
Posts: 514
Joined: Tue Jan 10, 2006 10:37 am
Location: Florence, Az.

Unread postby Ashman » Sat Sep 12, 2009 8:01 am

What is the core size of the radiator?
You should need about 20inX20in (not including the side tanks)
Are you using a shroud?

I couldent keep mine cool with a flex fan, I had to run two BIG electric fans a 12in and a 14in, its much better now, but marginal for highspeed stuff.
User avatar
Ashman
Site Admin
Site Admin
 
Posts: 5449
Joined: Wed Nov 27, 2002 11:14 am
Location: Vail, Arizona

Unread postby scramblerX » Sat Sep 12, 2009 9:27 am

401 factory setups are notorius for running cold. What vintage is the 401 (ie the compression ratio)? They also have a lot of vacuum at idle if they are remotely stock. Is the 12 degrees basic timing (vacuum advance disconnected, idle low enough not to have any mechanical in)? If so, that might be a little much, because a stock distributor may bring in another 32 degrees pretty quickly. I run that much in mine, but I've also done a lot of stuff with the timing curve and cam to make it happy that way. Let us know what your pieces are (or from) and I can look up just about anything for specs. IIRC, most stock were in the 0-5 degree basic range. Ditto what Dave said about flex fans - they suck. Their real purpose is to be a power saver. With rpm they just flatten out and stop pulling air (hence stop consuming hp). Bad deal in a vehicle with gearing where the engine speed is high relative to the radiator airspeed. And you definitely want a good shroud. If the radiator was a V8 CJ radiator, and it's 4 core, you might be alright with that if it's a stock/mild 401. An I6 radiator probably ain't gonna cut it, though. The later 360s had retarded cam timing (and yes, I mean that in every way it could be interpreted), so it's also possible that something could be going on there if parts were mixed at some point. Same deal if the timing chain is worn (loose). It's amazing what these things will run ok with when wrong.
Tim
User avatar
scramblerX
Supporting Member
Supporting Member
 
Posts: 669
Joined: Wed Jan 25, 2006 1:13 pm
Location: Tucson

Unread postby 1tonCJ » Sat Sep 12, 2009 12:27 pm

One thing I forgot to mention was that I pulled the distributor off my old 304 and put it on the 401. Looking at part numbers on the web, I figured they were interchangable. What do you guys think? I think it is pretty low compression because it has the bowl looking pistons (I can't remember what they are called) It is a 4 core radiator. I am not sure of the size. I don't have a fan shroud right now bacause I changed the engine height and the radiator sits higher. I did put a transmission cooler right in the middle of the Rad. and it is pretty big, do you think that could cause any problems?
-John C.
Tubed out CJ7, AMC 401, TH400 reverse manual valve body,Dana 300, 14 Bolt Rear, 60 Front, 47" LTB's, Hydro Steering
Its a work in progress, I just can't seem to progress!!
Just Empty Every Pocket
User avatar
1tonCJ
Mud Terrains
Mud Terrains
 
Posts: 514
Joined: Tue Jan 10, 2006 10:37 am
Location: Florence, Az.

Unread postby scramblerX » Sat Sep 12, 2009 12:58 pm

When and how is it overheating? Was this originally a factory 304 CJ, and what year? If the 401 has dish tops with 4 big valve notches, then it is likely 8.5:1, but some heads can make it 9.5. Does it have non-adjustable rockers (with the aluminum bridge between the rockers)? If so, then those are the lower compression (larger chamber) heads. If they are adjustable with screw-in studs what is the casting number? What do you know about the 401 (what did it come out of, etc).
Tim
User avatar
scramblerX
Supporting Member
Supporting Member
 
Posts: 669
Joined: Wed Jan 25, 2006 1:13 pm
Location: Tucson

Unread postby 1tonCJ » Sat Sep 12, 2009 10:57 pm

The 401 came out of a 75 Wagoneer. It does not have adjustable rockers. It overheats after a few minutes of running whether it is idling or driving around.

I just pulled out a brand new aluminum radiator from my storage that I basically forgot I had. It is just about the same exact size as my stock radiator but with bigger tanks on the side. inlet and outlet are in the same places. it is a two row radiator made by Howe. But the rows are alot bigger than the rows in my raditor and they are horizontal rather than vertical. It is about a 1/4 inch thicker than the stock one. I think it is the 2nd biggest they make when I look at the size chart on the web. would it be worth it to use the aluminum rather than rplace the stock radiator? Here is the link, my aluminum is the one listed on the top. number 3429.
http://www.howeracing.com/p-7821-step-1-cores.aspx
-John C.
Tubed out CJ7, AMC 401, TH400 reverse manual valve body,Dana 300, 14 Bolt Rear, 60 Front, 47" LTB's, Hydro Steering
Its a work in progress, I just can't seem to progress!!
Just Empty Every Pocket
User avatar
1tonCJ
Mud Terrains
Mud Terrains
 
Posts: 514
Joined: Tue Jan 10, 2006 10:37 am
Location: Florence, Az.

Unread postby scramblerX » Sun Sep 13, 2009 11:20 am

Is there a chance that your stock radiator got plugged up with oil/sludge from the 304's timing cover failure? Aluminum isn't as effecient as copper for heat transfer, but it's lighter, and the wider core tubes are more effecient than the skinnier ones. If your Howe is easily bolted in, it's probably worth a try. They are a good piece in racecars. I haven't heard anything about how they hold up off road. Had you driven the Waggoneer around to know if the motor wasn't overheating in it?
Tim
User avatar
scramblerX
Supporting Member
Supporting Member
 
Posts: 669
Joined: Wed Jan 25, 2006 1:13 pm
Location: Tucson

Unread postby 1tonCJ » Sun Sep 13, 2009 11:47 am

The guy I got the wagoneer from said everything was rebuilt 20K miles ago and then it just shut down, so he thought it was electrical. After putting it in my Jeep and it firing up, I would agree that it was electrical. I don't know if it was overheating in the wagoneer.
-John C.
Tubed out CJ7, AMC 401, TH400 reverse manual valve body,Dana 300, 14 Bolt Rear, 60 Front, 47" LTB's, Hydro Steering
Its a work in progress, I just can't seem to progress!!
Just Empty Every Pocket
User avatar
1tonCJ
Mud Terrains
Mud Terrains
 
Posts: 514
Joined: Tue Jan 10, 2006 10:37 am
Location: Florence, Az.

Unread postby 1tonCJ » Mon Sep 21, 2009 11:42 pm

I installed the new radiator, a new thermastat and set the timing to 8 degrees again and adjusted the Carb. then I took it for a spin. It warmed up to about 175 before taking off on the road and then it stayed around 200 degrees while driving about 30 MPH but it creeped up to about 220-230 when I was driving around 10 MPH. I think I just need to get more air moving at idle. My next project is a shroud then an electric fan. Any ideas?
-John C.
Tubed out CJ7, AMC 401, TH400 reverse manual valve body,Dana 300, 14 Bolt Rear, 60 Front, 47" LTB's, Hydro Steering
Its a work in progress, I just can't seem to progress!!
Just Empty Every Pocket
User avatar
1tonCJ
Mud Terrains
Mud Terrains
 
Posts: 514
Joined: Tue Jan 10, 2006 10:37 am
Location: Florence, Az.

Unread postby hayseed » Tue Sep 22, 2009 12:38 am

I'm running a dual fan set up , I don't know what it came from but it has mopar part numbers on it. it was in my jeep when I bought it. It is almost a perfect fit for my CJ radiator. I could look at the numbers if you are interested.
Rocking J Offroad
1941 W. Gardner LN.
Tucson, AZ 85705
(520) 834-4242
Specializing in rock crawler custom fabrication, chassis, suspension, and drive train.
Check out our website! http://www.rockingjoffroad.com
User avatar
hayseed
WAZ Vendor
WAZ Vendor
 
Posts: 764
Joined: Wed Aug 15, 2007 8:06 pm
Location: Tucson, AZ

Unread postby 1tonCJ » Wed Sep 23, 2009 12:27 am

hayseed wrote:I'm running a dual fan set up , I don't know what it came from but it has mopar part numbers on it. it was in my jeep when I bought it. It is almost a perfect fit for my CJ radiator. I could look at the numbers if you are interested.


Thanks. Let me see what the shroud does for me and if it works, I will be good. If not, I will get back to you.
-John C.
Tubed out CJ7, AMC 401, TH400 reverse manual valve body,Dana 300, 14 Bolt Rear, 60 Front, 47" LTB's, Hydro Steering
Its a work in progress, I just can't seem to progress!!
Just Empty Every Pocket
User avatar
1tonCJ
Mud Terrains
Mud Terrains
 
Posts: 514
Joined: Tue Jan 10, 2006 10:37 am
Location: Florence, Az.


Return to Jeep Tech

Who is online

Users browsing this forum: No registered users and 1 guest