401 high oil temp?

[Frank Z]

Well....I haven't checked the mechanical gauge yet but my modified 401 seems to run oil temps in the 230 to 255 range while cruising at 70mph with 70 to 85 :rolleyes: degree outside temps. All other fluids seem to be fine i.e. water/trans.
The engine runs very strong and was professionally built and assembled so any ideas on what could be causing this. I'm thinking about reinstalling the oil cooler.

Frank

[joe]

Frank, how much overbore did the shop go? The 401 can't handle a lot. Factory recommened max over is 0.0225 but most folks can get away with 0.030 over. Anything over that and it's an expensive gamble.

[Frank Z]

Joe,

Geeez.........that's a good question. I don't think it was any more than .030 though.
Ok.....lets look at the worst case......what if it was bored bigger. What should I expect? Can a good size oil cooler make the engine last for a while? I have a complete running 76 J-20 that my girlfriend had from her ex. It has been sitting since 91 with a rebuilt 401 with less than 10,000 miles on it and I recently thru some gas in it and got it fired up. So I have another engine to play with if need be.

Regards

Frank

[LRRH]

If its a much bigger bore your cylinder walls will be too thin!!! Which would be a major problem.

There's a member here by the name of Snakeyes who went insane and did .060 over and kept it cooled...i forget how though. If you search the post you may be able to find some threads about it.

[gsmikie]

where is your oil temp gauge hooked up at ?????

[Wesdog]

Originally posted by gsmikie:
where is your oil temp gauge hooked up at ?????Yeah, where is the sensor? I have a bung in the oil pan and use a mechanical gauge, I also have a 7qt oil pan. Depending on where you are measuring the temp, how much throttle you are using, the outside temp, your air/fuel mixture, timing, egr opertion or lack thereof and how well your cooling system is working, an OIL temp of 230 - 255 degF cruising @ 70mph may not be that all bad for a .030 over 401, I've had mine go above that climbing into the local mountains on a hot day. I would also want to bring it down a bit and your coolant temp certainly must be kept below 230degF. B&M makes a nice oil SuperCooler kit for AMC V8s. Includes a billet adapter, hoses and cooler. My recent cooling mods post showed where I mounted the cooler. http://www.ifsja.org/ubb/ultimatebb.php?ubb=get_topic;f=2;t=020127

[ June 23, 2003, 10:06 PM: Message edited by: Wesdog ]

[Frank Z]

Wesdog.....

Thanks...everything is mounted exactly the same as yours. We could have twins since my Jeep is almost a carbon copy of yours. Will post pic's........and by the way it's for sale for the right price someday :)

Frank

[Wesdog]

Frank,
I've only had my oil temp gauge installed for a couple months so don't have a lot of datapoints yet for comparison with the temps you reported. I did drive about 50 miles each way from my place near LAX up into the local mountains and back a couple weeks ago to look at some FSJ parts. I didn't have my oil cooler connected for that trip so other then the extra oil capacity there was no oil cooling except what the normal cooling system provides (my cooling system isn't anywhere near stock though). It was a hot sunny day and my oil temp was around 210 after everything got up to temp and I was driving on the freeway doing 70-75 mph. Going uphill as I approached the base of the mountain it would climb to 230. Once I started up the mountain my oil temp slowly increased to 280 degF. It cooled right back down to around 230 once I was past the uphill climb. My coolant temp got to around 210 if I recall correctly. I was averaging 50-55mph climbing from 1000' up to 8000' so I was pretty far into the throttle and the engine was working pretty hard. I wanted to see what it could do. There was no significant engine knock and the exhaust gas temps were around 1400 degF which is fine. However, an oil temp above 250 degF is not a good thing and without the gauge I would never have known the oil was getting that hot. It wasn't at that temp for long. I am going to be making the same trip again soon with the oil cooler hooked up so I will get a comparison http://www.ifsja.org/ubb/ultimatebb.php?ubb=get_topic;f=2;t=020127 , it better be lower, much lower! That's about all the info I currently have that might be helpful.
Wes

[ June 25, 2003, 09:19 PM: Message edited by: Wesdog ]

[Frank Z]

Wesdog,

Thanks for the input........I'm going to check two things before I reinstall the oil cooler.
First I'm using a Autometer mechanical oil temp gauge going directly into the back of the pan. I just realized that it might be a insulation/routing problem since the harness that the tube for the gauge is in is pretty close to the headers. Even though it is wrapped with some reflective foil tape that might not be enough and the heat might be influencing the capillary action of the fluid in the tube itself, will wrap it better or reroute it and let you know what I find out.
I'm also going to check the oil temp with another calibrated thermocouple and put it right in the dipstick tube to take the reading.

Frank

P.S. As soon as I figure out how to post some pic's of my Jeep on this site I'll send you a couple.

[Wesdog]

Frank,

I am also using an Autometer gauge and routed mine up the passenger side of the trans next to the trans dipstick tube to keep it away from the headers. Sent you a PM reply also.

Wes

[jeepsr4ever]

oil looses its lubrication at around 240 DO NOT RUN IT THAT HOT. use 2 cans of super coolant if you have to , you are wearing your engine out fast like that........230-240 youch!!

[Wesdog]

Frank, I made the drive up into the mountains again today but this time my oil cooler was hooked up. Outside temps were about the same as last time as was time of day and speeds. The oilpan temp sensor averaged about 210degF when cruising at 70-80 mph. When climbing the mountain it increased to just below 240degF near the end of the climb. The cooler is between the oilpump output and the engine so the oil temp at the bearings should be below the temp measured in the oilpan. The oil in the pan has traveled through the oil passages and picked up heat after leaving the cooler. As mentioned above I measured a max oil temp of 280degF previously so there was a 40degF difference in max temp when the engine was under a heavy load. That's a pretty good improvement in my book. Wes

[ July 15, 2003, 07:05 AM: Message edited by: Wesdog ]

[Frank Z]

Wes,

Thanks.........been busy so I haven't had time to do the same. I will let you know when I hook it up.

Thanks

Frank