High Flow Water Pump

[Brett Polwell]

My fresh 401 isn't running as cool as I would like. It usually falls between 210 and 220 going down the highway. The odd thing is that when I am idling along offroad it runs cooler. The 401 is in a yj. I have an aluminum radiator with the stock clutch mechanical fan. Everything is new. I have put two bottles of water wetter in the radiator with very little antifreeze. This helped quite a bit. I do have a shroud on it.

My question is whether or not a high flow water pump would help me out or hurt me. I have read countless debates but I can't find anyone that will give me a direct answer. If this won't help my next thought is louvers.

[1980_Cj7]

We were having exactly the same thing with our fresh new 401, running hot down the road but fine around town or at idle.

We already have a Flowcooler water pump, and a Taurus electric fan that blows like a hurricane. What we finally found was that if we backed off the timing, it made a huge difference. We were originally running 10¬? advance, and cut it back to 5¬?. We rarely get over 200¬? now unless it's really hot out, like 95¬?, and even then we stay under 210¬?.

The timing makes sense, and explains why it runs hotter at higher speeds/rpms, the timing advance.

We are running a 160¬? thermostat, and we added hood louvers, but I don't think they really lowered the temp any further. There's a very recent post in here on the louvers.

[Mcktiger74cj5]

hey guys im having the same problem in myrebuilt 360 23 miles she wont stay cool im talking 240. i burb it for a couple hours flex fan ,highflow water pump ,shroud. havent check timing did it by ear runs good tomorrow timing.

[1980_Cj7]

Check that timing ASAP. Too much advance causes an engine to run hot, and also causes detonation, which will destroy your engine in short order. 300 miles in our case.

[mrtazwrench]

Check that timing ASAP. Too much advance causes an engine to run hot, and also causes detonation, which will destroy your engine in short order. 300 miles in our case.

had one of my J20's start to do this after tweaking timing after a TFI conversion, never put a light on it just went on a drive/adjust trip, been good ever since.
I put a flowkooler on my other J20 over the winter, it was getting near 220, but I was going up a grade trailer on, and 4K loaded on the trailer, droped down some on the flat and going downhill, seemed fine unloaded also.

[Mcktiger74cj5]

put a clutch fan on this moring,adjusted timing to 7 degrees running 180 love it now in can break her in.

[Goose]

Let me offer my theory on this , just as food for thought.. As a general rule we lower our gear ratios on these jeeps just like street rooders do..which means going down the highway we turn more RPM than stock, which means we push the water through the radiator much faster than normal. and since a radiator absorbs heat from the coolant and gets rid of it by radiation. Clever name ehh? if the water is flowing through tha rad so fast that the coolant cant shed it's heat to the radiator then the water gets hotter by every circuit through the radiator. as it is retaining more and more heat with each pass..
When you slow down the coolant flows slower and it stays in the radiator longer allowing it to transfer more heat. (and since oyu put the wetting agent, a surfactant, in the radiator and it made a big difference that would lead me to think this is what is wrong with yours.. since a surfactant breaks the surace tension of the water molecules and allows them to transfer heat faster.
This is very similar to what happens when guys take the thermostat out and water free flows through the radiator..
So I sadi all that to say this.. I am betting that a high flow pump would make your problem worse (unless your pump is cavitating now..then the high flow might help cause they are designed to move water without cavitation.)

Hope something in this helps #-o

[dwg86]

I was kinda thinking alone the same line...While running down the road the water pump is pushing the water through a wide open thermostat and it doesn't stay in the radiator long enough to cool, but at idle the water pump slows down and the water is moving slower allowing it to cool. What about installing a 180 degree thermostat?

[1980_Cj7]

Makes sense, but I'm wondering, might that be a vicious circle ? While a higher temp t-stat is staying shut longer OR the water pump is moving water slower so it can stay in the radiator longer and get cooler, the water that is staying in the block longer is getting hotter. I guess the balance would come down to whether the water cools faster or heats up faster.

[Brett Polwell]

As far as the gears in my Jeep I am still running the stock 3.73 gears in the diffs with 37 inch tires. It tachs about 2200 rpm at 60. I would hate to see what the top end would be in this thing. I am also running a 727.

I bid on some hood vents on ebay. I don't think it will cure my problem but they should look cool. I think I need to upgrade my shroud. How hard would it be to make a cj v8 shroud work in a YJ. I hate to order a new one to find out I can't make it work.

I set the timing according to the DUI instructions that came with the Distributor. I think its advanced like 12 degrees, but don't hold me to that.

[1980_Cj7]

The big thing you need to worry about is the total advance, not just the initial advance. The faster you go, the more the timing advances by way of either mechanical or vacuum advance. You shouldn't be running over about 34 degrees total advance. If you are running more than that, that could explain why it runs hot at higher speeds and fine at lower speeds. We were having the same problem. We backed off on the timing and it runs much cooler now.

I'd be interested in seeing how DUI tells you to adjust the timing. I wonder if they have those instructions on a web page.

[AMX69PHATTY]

Some very very good Vacuum Advance Reading here:

http://www.stevesnovasite.com/forums/showthread.php?t=11689

:idea:

[1980_Cj7]

Wow! Great link. Just learned an awful lot. Thanks.

Now, we're running a distributor with mechanical advance only. Sounds like we should go back to vacuum advance. Engine is running fine, but sure is using a lot of gas. Wonder if the vacuum advance will help. And if more advance is needed at idle, we're really hurting with no vacuum advance and our intial timing way back to 5 degrees.

[AMX69PHATTY]

Wow! Great link. Just learned an awful lot. Thanks.

Yeah, me too, have ran with no vac adv can for like 15 years.

[1980_Cj7]

I have always known that the vacuum went away when you got on the throttle, but never made the connection that therefore so would your vacuum advance. Duh! I just always wrongly assumed the faster the engine went, the more advance you got from the VACUUM advance. (I knew all distributors have mechanical advance, even distributors with vacuum cans.) Never knew you wanted more advance at idle either.

Guess knowing that
1. timing has to increase with engine speed, and
2. the vacuum advance mechanism is there to advance the timing
led me to subconsciously (in other words, WITHOUT THINKING) make the connection that the faster you went, the more vacuum advance you got.

[JERSEYJOE]

What a great article.

[ironman_gq]

thats why rolling on the throttle is better than mashing it to the floor and hoping for the best :lo1l: