high flow oil pump & water pump for 4.0

98zjstroker

98zjstroker

Well-Known Member
Joined
Oct 14, 2009
Location
concord nc
Ok so my jeep 4.0 stroker is done! well for the most part. Just need to through the head on and oil pain and put it back in the jeep. I am ordering a new oil pump and water pump to protect my investment. I am looking into a high flow (not high pressure) oil pump and water pump. This is in hopes to keep the temps down while off roading. Also I had to have to motor bored .040 over which im sure can/will cause some issues running hot.

My questions is, is this worth spending the extra money on both or either one of these? Anyone actually used these on their builds? I dont want to spend the money on something that I dont need or wont make a difference.

If you do recommend them brand and/or where to go?
 
I seem to remember some saying a high flow wp can cause overheating due to not having time to cool in the radiator. I could be wrong but I remember something like that.
 
obullfish said:
I seem to remember some saying a high flow wp can cause overheating due to not having time to cool in the radiator. I could be wrong but I remember something like that.
Click to expand...
This can be true depending on pulley diameter and impellor diameter. Too fast and it will flow too fast to cool properly in the radiator.
I've seen way too many performance strokers and performance 4.0s use OEM items with great success.
 
Jody Treadway said:
Melling OEM type oil pump. No need to church it up.
Good quality OEM type water pump. Again with the church.
A properly functioning OEM cooling system will cool the extra displacement just fine.
Been there, doing that.
Click to expand...

OK will def order the OEM water pump, with that the melling oil pump it shows that the stock OEM will be $103 with the screen but only $97 for the high volume melling which includes the screen. So cost would be actually cheaper to get the high flow from autozone vs the regular OE. Is there any issues getting the the HV one in this case?
 
You need 10 psi per 1k rpm. Do you need a high volume oil pump? No. If you go that route, be sure to upgrade the distributor gear. And run 5w30 winter and 10w30 summer.

I run a high volume in my 4.7 stroker.

Go stock cooling. Will be fine.
 
Jeff B said:
You need 10 psi per 1k rpm. Do you need a high volume oil pump? No. If you go that route, be sure to upgrade the distributor gear. And run 5w30 winter and 10w30 summer.

I run a high volume in my 4.7 stroker.

Go stock cooling. Will be fine.
Click to expand...


why the distributer gear?
 
Pump ratio, trying to move larger volume of oil. Puts more stress on the distributor gear, especially in colder weather. So one must pay attention to oil weights.
 
obullfish said:
I seem to remember some saying a high flow wp can cause overheating due to not having time to cool in the radiator. I could be wrong but I remember something like that.
Click to expand...

Complete and absolute myth. The longer the water stays in the radiator, the smaller the deltaT is, and the less efficient thermal transfer becomes. The slower the flow, the worse the cooling becomes. The faster the flow, the higher the deltaT remains, and the higher the efficiency stays.

If you're driving a high flow pump within its efficiency range and not having problems with impeller cavitation, more flow is always better. I've always assumed those type of things are the reasons people would get poor cooling with a high flow pump (too many system restrictions can create too much pump head and cause impeller cavitation, things like that). Or people just pick the wrong pump and drive it at the wrong RPM or use the wrong pulley ratio or whatever.
There is definitely a point of diminishing returns though, where more flow doesn't add enough additional cooling to makeup for a compromise somewhere else (like pump RPM range, or whatever).

This all assumes that you actually need more flow though, and aren't already well-served by the OEM pump design.
 
Last edited:
Fabrik8 said:
Complete and absolute myth. The longer the water stays in the radiator, the smaller the deltaT is, and the less efficient thermal transfer becomes. The slower the flow, the worse the cooling becomes.

If you're driving a high flow pump within its efficiency range and not having problems with impeller cavitation, more flow is always better. I've always assumed those type of things are the reasons people would get poor cooling with a high flow pump (too many system restrictions can create too much pump head and cause impeller cavitation, things like that). Or people just pick the wrong pump and drive it at the wrong RPM or use the wrong pulley ratio or whatever.
There is definitely a point of diminishing returns though, where more flow doesn't add enough additional cooling to makeup for a compromise somewhere else (like pump RPM range, or whatever).

This all assumes that you actually need more flow though, and aren't already well-served by the OEM pump design.
Click to expand...
Like I said I could be wrong. This is the best way to get the correct answer that I’ve found. :D
ED39EC73-2A23-4B3E-AE32-62FC65997D78.jpeg
 
No need for anything more than high quality water and oil pumps.

I have a stroker bored .040 over with stock style YJ water pump, radiator, fan, and fan clutch.

Hottest it gets is 220 in high load/low rpm crawling areas. On long uphill medium rpm pulls when all my buggy friends are hot with electric fans, I’m at 195.

Only thing that made a significant difference is the poison spyder hood vent panel. Let’s the build up of hot air out from the hood. Keeps the heat soak down.

You need 10 psi oil pressure for every 1000 rpms. Melling stock pumps will do that no problem.

Low oil pressure when hot with 4.0’s usually means too much bearing clearance/worn bearings. As long as your clearances were good, a stock type good high quality replacement oil pump will be fine.
 
^ what they all said.

Now as far as the radiator goes... I had a yj come in, aftermarket radiator - it would run warm (225 or so) at idle, sitting. Take it down the road and it would cool off. I had installed my used yj radiator to test whether the radiator was causing running hot after doing the head gasket, wp & tstat, so I knew all that was good - and it would not even hit 210* idling. The new aftermarket rad was 3/4" thinner than the factory rad. That was after flushing the block with the head removed. So I would say if you are concerned with cooling - upgrade to a 2-3 row rad that is thicker than the factory unit. I've never had any issues with water pumps or thermostats not allowing enough flow - leaks, yes (5 water pumps in one year on my xj - with no other issues present with the cooling system - the seals kept leaking after 2-3 months). I did not have any issues with aftermarket xj radiator as they were the same core thickness as the original. The yj rad was the exception and only case of insufficient cooling(from what should be an OEM equivalent) I've ran into in the 15 or so years I've been working on vehicles professionally.
 
Just here to second what the others said. If you can find a stock water pump that will last, great. I went through just about every brand/vendor and eventually the cheap chinesium bearings would fail and make the pump leak. I went to a flowkooler pump just because of the better bearings and it’s made in the USA. The higher flow is a bonus that I don’t really think is needed, but it’s nice to know it won’t fail within a year like the parts store brand pumps.

I did have cooling issues with the stock XJ radiator when it was hot out, but that was when it was over 85 outside with the a/c blasting doing 70+ on the highway. I went to a thicker 2 row radiator and it helped keep the temps reasonable. I have to shut
 
Last edited:
Ok so I just got in the oil and water pump. Oil pump has been installed. When I got the water pump out of the box I noticed that it does not turn as freely and easily as the old one. It feels much "tighter." I does not feel like its grinding or turning rough as if something is catching or bad. It just is harder to turn and wont continue to spin on its own when I try like the old one.

I feel like this would be normal with a new one and assume it has more resistance to it compared to an old used one. But call me paranoid but I dont want to put a bad water pump on my new motor.
 
84jimmy said:
Ok so I just got in the oil and water pump. Oil pump has been installed. When I got the water pump out of the box I noticed that it does not turn as freely and easily as the old one. It feels much "tighter." I does not feel like its grinding or turning rough as if something is catching or bad. It just is harder to turn and wont continue to spin on its own when I try like the old one.

I feel like this would be normal with a new one and assume it has more resistance to it compared to an old used one. But call me paranoid but I dont want to put a bad water pump on my new motor.
Click to expand...

95% of that is seal drag from the new seals.
 
New question. Didn't feel like starting a whole new thread for it cause I am sure I will have more later. But anyone's thoughts on ARP head bolts for the 4.0 stroker build? I know I am probably overthinking it but wasn't sure if I should spend the extra money on them. Found the exact arp stud kit I need for around $140. Dont want to spend that much but with the increased compression and power if I need them I will.

So what do you guys who have already dont the build suggest, ARP or stock replacement? again I am at the dilemma that I do not want to cheap out on a part that I may actually benefit from but also dont want to waste money on stuff that isn't needed.
 
84jimmy said:
New question. Didn't feel like starting a whole new thread for it cause I am sure I will have more later. But anyone's thoughts on ARP head bolts for the 4.0 stroker build? I know I am probably overthinking it but wasn't sure if I should spend the extra money on them. Found the exact arp stud kit I need for around $140. Dont want to spend that much but with the increased compression and power if I need them I will.

So what do you guys who have already dont the build suggest, ARP or stock replacement? again I am at the dilemma that I do not want to cheap out on a part that I may actually benefit from but also dont want to waste money on stuff that isn't needed.
Click to expand...

I’ve seen builds were people welded on a turbo flange on the exhaust in a parking lot and ran it bone stock engine. The head didn’t come flying off :D


Sent from my iPhone using Tapatalk
 
84jimmy said:
New question. Didn't feel like starting a whole new thread for it cause I am sure I will have more later. But anyone's thoughts on ARP head bolts for the 4.0 stroker build? I know I am probably overthinking it but wasn't sure if I should spend the extra money on them. Found the exact arp stud kit I need for around $140. Dont want to spend that much but with the increased compression and power if I need them I will.

So what do you guys who have already dont the build suggest, ARP or stock replacement? again I am at the dilemma that I do not want to cheap out on a part that I may actually benefit from but also dont want to waste money on stuff that isn't needed.
Click to expand...


the 4.0 manual says you can reuse the head bolts twice. These are not torque to yield. I have reused head bolts several times without incident. Don't waste your coin on ARP head bolts unless you're going turbo with lots of boost..
 
Jeff B said:
the 4.0 manual says you can reuse the head bolts twice. These are not torque to yield. I have reused head bolts several times without incident. ..
Click to expand...

Stupid question what is torque to yield?

Do I need to bolt them back in the same spots they were before or does it not matter??
 
84jimmy said:
Stupid question what is torque to yield?
Click to expand...

When the bolt begins to stretch.

84jimmy said:
Do I need to bolt them back in the same spots they were before or does it not matter??
Click to expand...

yes, for your harness rail and the alignment bolts of your valve cover gasket. other than that I don't believe so. Be sure to put the correct sealant on bolt #11 and torque in the correct pattern.
 
Two lengths of bolts. Pass & driver. Depending year, two shorter head bolts have Guide pin for the valve cover gasket. Other than that no. Also #11 gets sealant & torqued to 100# not 110# like the rest.
 
Back
Top