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Not Your Average Cooling System Problem
Posted: September 17th, 2018, 2:34 pm
by sandfreestyle
I’ve been trouble shooting this cooling problem for months and I just can’t figure it out. I've read countless thread on multiple forums, read repair manuals, read the FSM, laser temp check everything, still can't figure it out
Installed a new 4.7 stroker about a year ago and since then I have been having a very odd cooling system gremlin. When I first start up the car it gets to about 195-200* and it will hold there for about 5 min/miles then it will creep to 210* for another 5min/miles and then start creeping to 225*. It holds there while driving but when start/stop traffic happens it will just slowly creep up. Even with the electric fan it will only hold at that temp or very slowly creep. I can’t figure out why this is happening.
94 XJ with 4.7 stroker w/ about 1,500ish miles (mainly freeway easy driving)
New 180* t-stat
New temps sensors (t-stat housing and back of block, both reading within spec)
New high-flow water pump
New upper and lower re-enforced hoses
New aluminum 3-row radiator
16psi cap
ZJ fan clutch (working properly via drag when cold and stops spinning when shut-off hot)
97+ aux fan
60/40 coolant mix
Timing is dead on
14.5-14.8 AFR (on the smog rollers)
26lbs injectors @ 50psi (per builder’s specs)
91 octane fuel only
Re: Not Your Average Cooling System Problem
Posted: September 17th, 2018, 7:15 pm
by jsawduste
sandfreestyle wrote: ↑September 17th, 2018, 2:34 pm
I’ve been trouble shooting this cooling problem for months and I just can’t figure it out. I've read countless thread on multiple forums, read repair manuals, read the FSM, laser temp check everything, still can't figure it out
Installed a new 4.7 stroker about a year ago and since then I have been having a very odd cooling system gremlin. When I first start up the car it gets to about 195-200* and it will hold there for about 5 min/miles then it will creep to 210* for another 5min/miles and then start creeping to 225*. It holds there while driving but when start/stop traffic happens it will just slowly creep up. Even with the electric fan it will only hold at that temp or very slowly creep. I can’t figure out why this is happening.
94 XJ with 4.7 stroker w/ about 1,500ish miles (mainly freeway easy driving)
New 180* t-stat
Should be a Factory Mopar 195.
New temps sensors (t-stat housing and back of block, both reading within spec)
New high-flow water pump
Stock works just fine
New upper and lower re-enforced hoses
New aluminum 3-row radiator
That's not an improvement and is most likely your biggest issue. It might be 3 rows but to fit the vehicle those 3 rows may actually have less surface area. Id also bet the fin count is such that it is more restrictive to airflow.
16psi cap
ZJ fan clutch (working properly via drag when cold and stops spinning when shut-off hot)
97+ aux fan
60/40 coolant mix
Timing is dead on
14.5-14.8 AFR (on the smog rollers)
26lbs injectors @ 50psi (per builder’s specs)
91 octane fuel only
Get a stock OEM radiator and a stock WP. The factory guys are pretty smart and they spent a lot of time designing a cooling system that works pretty good. Vast majority of aftermarket parts are a step backwards. Remember aluminum absorbs heat well but doesn't rid itself of heat so good.
Re: Not Your Average Cooling System Problem
Posted: September 17th, 2018, 11:20 pm
by Cheromaniac
I was also going to suggest that the radiator is the problem. Aftermarket radiators cram three rows instead of two into the same (or only slightly greater) thickness, resulting in the passages being smaller than stock.
A new two-row OEM radiator should alleviate the problem.
Re: Not Your Average Cooling System Problem
Posted: September 18th, 2018, 9:11 am
by sandfreestyle
I had a 2-row radiator and had the same problem, but the only thing I haven't changed is the pump. I did do the restrictor in the hose (tried 1/2, 5/8, and 3/4) with no effect.
I tried "burping" the head by pulling the temp sender in the head while on a steep hill, even dropped on air in the front tires. Was at about 30* butt high when done.
Lower hose is not collapsed at all.
I'd have to get a pic of the plugs, but I've tried normal Champions, Champion Iridium, E3, colder Champions and with same results.
Tried fuel pressures at 39, 50, and 58 psi on the rail.
Re: Not Your Average Cooling System Problem
Posted: September 18th, 2018, 8:20 pm
by LRSimons
Try the hood spacer thing. With that and wrapped header along with no ac stuff I can drive around with no fan just fine. Granted it doesn't sit in traffic or run trails but as long as it's moving it stays cool.
Re: Not Your Average Cooling System Problem
Posted: September 18th, 2018, 8:31 pm
by sandfreestyle
I have a fully functional cowl induction hood
Re: Not Your Average Cooling System Problem
Posted: September 19th, 2018, 12:39 am
by BcurpKodiak
I don't think your T-stat is your problem. But for some reason everyone still states that you should stick to factory which is only true if you're not doing any tuning. I run a 180° high flow and am tuned for it (has to do with open/closed loop). When you open it sooner you don't only tend to have slightly lower temps but you have more tame temp swings above 200° which allowed my tuner to give it a littler more timing. Just my .02. The internet is ripe with people telling everyone to run a stock 195° which I followed at first and found through experience that generally speaking it's false.
Re: Not Your Average Cooling System Problem
Posted: September 19th, 2018, 10:55 pm
by I6FAN
OP, I didn't see where you mentioned you had a "standard" or "reverse" rotation water pump. That could be a problem for sure!
Re: Not Your Average Cooling System Problem
Posted: September 19th, 2018, 10:58 pm
by I6FAN
Oh, and same with aux fan spin direction(?).
Re: Not Your Average Cooling System Problem
Posted: October 14th, 2018, 4:12 pm
by SIXPAK
I6FAN wrote: ↑September 19th, 2018, 10:55 pm
OP, I didn't see where you mentioned you had a "standard" or "reverse" rotation water pump. That could be a problem for sure!
Ive seen this more than once!