4.2 overheating with new water pump

4.2 overheating with new water pump

wrangler rider

Active Jeeper
the south
95 wrangler with 88 4.2 carbed with puguetoe(?) 5spd both fresh rebuilds, spring over, 3inch body, spring arched 2 inches and stiffened, 10 inches of total lift on 36inch tsls 8k mile marker winch, ect.
1969 dodge charger rt se 440, 727 torqueflite 3.55 suregrip with 8 3/4 axle, everyone is making her a headache for me but i love her 1000xs more then my jeep
2005 dodge 3500 cummins 6speed dually work truck, not mine
I had rebuilt my 4.2 last year and ran the old water pump, it finnally blew the seal and was leaking so i got a reman water pump put it on and realized i had crossed my intake and heater lines (heater to water pump and thermastat housing to intake) it had run at 190 degrees solid like that, and now i have the new pump and i switched the lines and she wants to run at 210 degrees now, same thermastat, no leaks, mechanical temp sensor, and i havent let it idle at 210 long enough to let it drop or increase, should i recross the heater and intake lines? since the temp sensor is in the intake it should make a difference, but i want which ever is accurate and i have constant 40-70oil psi
thanks yall:chug:
PS never put a ford starter solinoid on a 4.2 itll work but when the motor starts it keeps the starter engaged for 6 seconds after you let go of the key, everytime, take the soliniod off and it works fine, so hopefully u dont waste 2 days on it like i did
Check which water pump you got.

There are 2 different water pumps for that engine, one for serpentine belt and one for v-belt. The one for a serp belt engine will spin backwards on a v-belt engine. in other words one is a reverse rotation waterpump. That may be why you are over heating now and you weren't before you changed the waterpump.
The pump looked correct when i installed it, i switched the lines back yesterday (waterpump to intake to heater to thermstat) which is reverse of what hanes showed it to be but it sure as heck took 20 degrees of and im back at 190, so if you have a 4.2 switch your lines and run cool!!
thanks 3 quarterton, but i am happy that wasnt the case!
New guy here, I have a 1986 CJ7 with a .258, I also just replaced the water pump with a new not reman (old one was leaking) and the guy at the parts store assured me it was the right water pump but you never know. I did not change the thermostat, I did have the radiator repaired it was leaking also and now I am having a over heating issue which I was not before. I am wondering how do you tell if you need a v belt or a serpentine water pump. Besides taking off the water pump again. Or should I start with the thermostat. Thanks.
you might be able to tell by the part number, but id go back with the receipt and make them look up a few different ones yours and a v belt just to be sure, what temp does it get up to? if you know and make sure u filled the radiator after the therastat opened u could have a massive air bubble messing with you
good luck!
I don't have a working temp gauge (next on the todo list) but I only went about 2 miles and you could smell coolant when I popped the hood the rad was steaming and when I went to open the rad cap it was so hot I could barley touch it. The motor is supposedly a rebuild. Any help is appreciated.
No CJ that I know of had a serpentine belt set-up from the factory. The wranglers did tho.

Basically you would have your parts guy pull out a water pump with the same part # that you purchased and installed, and check it with the original water pump that you removed from the engine, and check to make sure the "fins" or "blades" are angled the same way on both water pumps. If you have a reverse rotation one in place of a regular rotation one, it will cause cavitation of the coolant, which will create over-heating.

Other wise Mr. zombiehunter I feel as though you are dealing with an air pocket trapped in your cooling system.

I've never seen a CA emission CJ that was intact yet. So to be honest I'm not sure if they had serps or not. :confused: Maybe Busa or Old dog will chime in on that one.

I see on that link though that 81's and 82's could've had serps. That's news to me lol, I guess you learn new stuff every day.
I see that the v belt is for engines without A/C mine has an A/C although like an idiot i threw away the old waterpump as i replaced it a two weeks ago and just got everything else put back together that I was working on so I cannot check the rotation with the new one. If it was a v belt stlye would there be two belts instead of one?????
I've never seen a CA emission CJ that was intact yet. So to be honest I'm not sure if they had serps or not. :confused: Maybe Busa or Old dog will chime in on that one.

I see on that link though that 81's and 82's could've had serps. That's news to me lol, I guess you learn new stuff every day.
My 86 CJ7 has a serp belt but the power steering has a v belt. It came from CA i bought it from the original owner he said it came like that stock.
your very lucky the rad cap was too hot to touch or youd be called scar face for the rest of your life, go to the parts get the triple gauge set up (cheaper then the oil sender unit aloneand more accurate) mechanical temp and oil gauge and amp gauge, buy a new rad cap, put it all in start it with out the cap on and watch the rad level and temp gauge, alot of collant will pour out the rad before the thermastat will open, its very anoying but normal, when you think its full and at the max idle temp according to your new gauge, rev the motor from the carb and watch the rad level it should drop when you rev it and raise when you let off at 190 degrees if the level doesnt move your probably got dupped by the parts tard, good luck but get a mechanical temp gauge!!!!! i ruined my crank, cam and all bearings in my motor from lacking of a oil pressure gauge and temp gauge, dont do the same!
I found my receipt and the part # matches the waterpump listed on their web site a with serp and reverse direction which is what I believe I needed. Also I changed the thermostat just now, jacked up the front end and started it up. After about 10min+- and a few bubbles then the coolant disappered. I let it down and went the exact same distance as last night and it no more hot smell and the cap was just warm to the touch and no steam puffing out. I think I fixed it. Now I just need to figure out the temp guage but that will be a new thread as I will need to go into detail. Thanks to all for the responses.:chug:
I know I am stealing this thread for that I apologize. My 86 CJ7 w 4.2 needed a new water pump, I put one on it is a serp style with reverse rotation I checked my receipt and that is the one they sold. me here is a really rough drawing of what things look like using what I can picture in my head I not with the jeep right now.

Any way I put the water pump in, had rad repaired, changed thermostat and finally got it to burp, took it for a ride and everything seemed fine, then last night it kind of smelled hot so I pulled over and touched the rad was warm but not hot. I felt the upper rad hose and it was hard as a rock the night before it was not. Attempted to open the cap and there was a lot of pressure. Any thoughts. I bought a new rad cap and I am going to install a mechanical temp gauge tonight. I can't afford the shop fees right now so I am trying to do this by myself.
hows the fan clutch? my 85 is a w/cali serp setup had a bad fan clutch. did everything you did as well just to be safe.
CA models as far back as at least 1981 had serpentine belts. If you look from the front, the pump turns counter-clockwise.
well i sat idle for about 10 minuits and watched the temp creep from 190 up to almost 220, im thinking its the fan clutch, so im going to try straight ounting the fan to the water pump (clutches are for standard trannys in my eyes) and or im going to put in a 175 thermastat, but im tired of this bs lol

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