My Willys 3A and 3B Community
TECH FAQ SECTIONS => Engine compartment => Topic started by: rcsteuer on August 05, 2024, 08:37:00 PM
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I have a '49 - 3A that was rebuilt 2 years ago (less than 2,500 mi.) and always runs hot. I've swapped the thermostat out from a 180 to a 160 and have tried the thermostat with and without the drilled holes. The change from the 180 to 160 brought the temp lower but still not where things should be running.
the issue is that under 35 mph, everything runs at around 175 - 180, but as soon as speed is increased or if there's a long hill, temps will hit 190 -195. Although it never overheats to the point of blowing off steam, there are side-effects. After running at those temps, shutting off the vehicle results in the temp jumping to 220 - 225, which causes the radiator to spit water out of the overflow tube - not a lot, but always. While it will start when it's been overheated, it's always harder than a cold start or when it remains below the 180 level.
I've futzed around with timing using tach, dwell and vacuum, as there are no marks on these. Dwell is 40, tach 670, vacuum 20.
Any suggestions? I've tried every trick in the book I know of. Maybe someone has a different book?
Thanks
PS radiator cap is new 4lb.
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How much over-bore?
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.060
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That is your problem. Throughout the production lifetime of these blocks, some wound up with thin to begin with cylinder walls. Boring out to 60-over only diminishes the ability of the iron to transfer heat effectively. For this reason, I advise all owners doing rebuilds to sleeve them back to standard.
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Hmmm, interesting. I worked in an automotive machine shop for years where we rebuilt engines, including a number of L4-134s (only shop within 150 mi. that could pour babbit bearings and line bore), and never ran into an issue. It's been too long (over 40 years) since then, so don't recall original wall thicknesses. Not suggesting you're wrong, just an observation.
So, if that's the case - where it's a matter of poor transference of heat - have you had any experience with running a larger radiator and/or flex fan, which should provide a bit of relief. If you can transfer heat out of the radiator, it should run a bit cooler.
Maybe someday, I'll drop the pan and mic the walls, just for the helluvit.
Thanks for your comments
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Assumptions follow:
IF your coolant is mixed properly, you should not boil over. IF your radiator cap is holding pressure, you should not boil over. IF you aren't leaking fluid, you shouldn't boil over.
You didn't state the condition of the radiator. Has it been cleaned/rodded to ensure no blockage? Is there belt slippage on the pump (impellers intact)? Bottom hose collapsing or restricted?
I "think" that if you're cooling at idle/low speed but at higher rpms you experience overheat my mind goes to circulation restriction. I could be wrong (happens a lot) and Scoutpilot is on to something I know little about.
I had a brand-new thermostat out of the box, stick on me. Testing in a bowl with a thermometer confirmed it. It seems your problem still exists even with a cooler thermostat (which makes me think circulation).
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What mixture of coolant are you using? Synthetic? Are you allowing the motor to cool for a minute before shutdown?
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I know this is an older thread I haven't updated due to being out of commission for a while. Warmer weather returning to the Northeast has allowed the CJ out of the barn.
Still same issues and I'll (finally) respond/answer prior questions. all of the following done during the rebuild before the jeep was ever run after rebuilding:
1. The radiator was boiled and flow-tested before installing
2. Two different 160-degree thermostats with the bleeder hole drilled. Both tested before install and opened at 160.
3. Antifreeze is ethylene glycol based Prestone, mixed at 50/50.
4. New 4# cap
5. New water pump
6. No sign of the lower hose collapsing
There are actually 2 things that I conflated into a single problem:
7. After running the Jeep to normal running temps (<180) and parking, the temp increases while parked and the cap will release fluid as soon as the temp reaches approx. 220.
8. When driving uphill for more than 5 - 10 minutes, temp will approach 200 and engine starts pinging. Stopping for a minute, brings temp down so that pinging stops and power returns to normal.
What's been done to try to correct overflow at rest:
9. Changed out cap. to the 2nd 4# cap to be sure it wasn't a cap issue.
10. Adjusted timing by retarding slightly (without timing marks, it's a crap shoot). I've been on both sides of optimal running - either too much pinging or too little power. As it sits now, the power is excellent until the hill issue pops up. Dwell at 39, tach at 670, vacuum steady at 20
11. Added the shroud to the radiator, which helped somewhat, but did not resolve the issue.
Because the cap releases when parked, I've just ordered a 7# cap. While reluctant to put a 7# cap on, I'm hoping to see if it prevents the overflow, figuring the loss of fluid may be contributing to the overheating.
ScoutPilot - if you're still monitoring - running an engine lean could contribute but I'm not seeing any indication of running lean. If anything, it's probaby running a tad on the rich side.
Any comments are greatly appreciated.
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Mine seems to be running a little better temperature after I replaced the thermostat retainer.
The new one was longer and sits against the head instead of relying on a friction fit like the old one.
The only logical explanation I can come up with is the old retainer was allowing coolant around the thermostat and circulating so quickly the radiator couldn’t cool it fast enough.
It wasn’t the cure because the temperature still climbs when pulling long hills, but it did seem to help to some extent.
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The pinging under load indicates a too-lean or too far advanced timing condition. What fuel are you burning?
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Trying to decipher this latest post, I'm leaning towards timing.
Your 3A is early. According to what I've read, there's a timing inspection hole at the back to see the timing marks on the flywheel.
https://cj3apage.com/Forum/index.php?topic=3432.msg28720#msg28720
Some have added a bolt on timing mark that will at least give you marks up front. This bolt on timing mark will need a notched pulley so that you can measure.
I initially had no idea you were running without a shroud. Good that you've got it on now. And YES, multiple seemingly irrelevant details can compound a problem.
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Thanks for the replies:
Scoutpilot - running 87 octane. I bring timing to highest, smooth-running point, then retard about 100 rpm, and adjust idle to ~670. Vacuum is steady at 20. I've pulled plugs and, while not full of carbon, are definitely on the darker side, so I've been assuming it's running a tad rich, if anything. I rebuilt the carb and even took it apart a second time to verify the metering rod settings, etc. It starts fine cold and when it's warm but hasn't heated over 200. When hot, it can be stubborn. Under those conditions, where the engine has been heated, harder starting may be an issue of vapor lock (?).
Russ, yes, very early - in fact, I've found a few items that were left over from the 49-2A. Rear end is a Dana 41, not a 44. The original engine rear plate was replaced but the plate that's on it does not have the timing hole, so it's a crap shoot. The crankshaft pulley didn't have a timing mark, so when i was reassembling the engine, I brought the engine to TDC and notched a mark as close as I could to the 0° mark on the timing cover. Not perfect, but it gave me a ballpark reference point.
Any other suggstions are welcome.
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All interesting. Since you say specific degree ranges, I'm "guessing" you're using an auxiliary temp gauge of some kind. Dare I ask "where" that temp-sensing is done, and is it internal, or "external temps" via a "digital Lazer gun" aimed at locations on the block or head? Using a gun, I've seen temps of cylinders on top of head vary drastically up to 30 degrees... like #1 @ 173, #2 @ 183, #3 @ 203 (Note: factory temp sensor location under that part of the head), and #4 @ 190. Those temps were taken with a 180 degree therm warmed up to "operating temp". Has anyone else done "head surface temps" and gotten similar results? Could the "perceived temp numbers" be throwing a curve to where your problem is???
As a suggested "bandaid"... an added "temp activated electric fan" could boost the cooling as "needed" when "temp activated", like at "rest" when "parked", or under heavy heat load conditions... cheaper than a new block. Good Luck!
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Thanks for the reply, SteveKfl. Using the analog temp gage that has the sensor mounted directly in a port on the head. While the absolute numbers may not be perfectly accurate, the differential is what's concerning and causing the problem. While driving at 40 mph on relatively flat roads, the temp will range from 165 - 180. As soon as I hit a hill > 1/2 mi, the temp will rise to >195 and it starts pinging.
As a test today, I retarded the timing so that the vacuum was just starting to fluctuate a bit and set the idle screw a bit richer to try to help with running at idle after heating up. Took it out for a spin and no difference.
I found a spacer that was made to move the fan blade closer to the radiator. Going to give that a try.
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From what I have read about cooling, the fan is primary when low speed and idle - as there isn't enough airflow to adequately cool the fluid. At speeds roughly above 35 mph, the fan is useless. There is enough ram air flowing through the radiator to keep the coolant from getting too hot. The shroud helps direct the air so that the fan is more efficient. I've always looked at the flow, through the filler neck, to reassure me that there's good circulation. I just recently read of a way to check the thermostat while it's still in the vehicle. Use a thermometer (I'm hoping those laser versions will work also) and measure the temp at the top of the coolant level just as the flow stops, i.e. the thermostat is closing. Clever.
Your issue is under load/ at speed. To me the pinging noise is a symptom. I'd hesitate to speculate as it may lead this discussion off into an unrelated rabbit hole. I think your timing adjustment for testing was a good idea. Have you observed any difference in oil pressure when the noise starts?
After you shut down, it continues to overheat to 220. That's concerning. To me it should be: if no fire, then no heat. Sitting hot is one thing. Temp climbing is different. Where are the thermostats coming from that you've experimented with? Local, brand name, or mail order?
Item 6 above on the 26 April post. "No sign of the lower hose collapsing." When it's not hot, can you squeeze it flat like the upper hose (open cap to allow displacement)? There should be a coiled wire (or similar) inside to prevent this. I've seen them fall out before.
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Be careful with the fan relocation "closer to the radiator" and deeper into the shroud. That can cause cavitation as there is less air "exit". I've always heard that the back part of the fan blade should be just outside the shroud.
I agree with Rus. Pinging is a clue. I'm wondering now if the "new" water pump (You said "same HOT situation from the beginning") is not pushing sufficient water for "loads", but just enough with the help of the wind of "driving" to keep things cool, while the other two conditions expose the "trapped heat"???
Do you have a heater? Turning it on adds an extra little radiator temporarily. Also, a clear heater tube substitution could show "flow" visually.
Is there a "vacuum advance" on the distributor, and if so, is it working properly? Just throwing questions out there, probably already answered. I can't wait to hear what the "fix" is.
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Thanks again, SteveKfl and Rus.
Yes, pinging is definitely a symptom, but the root cause is the mystery.
Actually, Russ, it may be time to head down different rabbit holes, as the ones I've been down, turn up no rabbits.
It's been nearly 50 years since I did a CJ rebuild but seem to recall the temp climbing after shutdown. I can rationalize that if the water is sitting in a hot block with no circulation, it will climb until the entire block starts cooling off. I can also rationalize that once you shut an engine off, it should be at its max temp and should not continue to rise. Given my complete lack of knowledge on thermodynamics, I assume one of them is correct but beats the devil outta me which one it is.
Could be the water pump might be the issue. Haven't gone down that path yet, but not far from it.
No heater in it, Steve. It has a mechanical vacuum advance that appears to work. I have a mark on the front pulley that I use a ballpark reference and when I rev the engine with a timing light on it, I can see the mark advance. And thanks for the heads-up on the spacer for the fan. It's worth a try ato see what the effect is. If that doesn't work, I'll tackle the water pump.
Appreciate the help.
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I think the temp climbing after shutting down is reasonably normal. But then I still a have some issues with it running hot at times.
Not that it couldn’t be the water pump, but the impeller should be cast iron and there’s very little to go wrong. Most of the time the seal goes bad and it’s easier to replace the pump than rebuild.
There is a vendor advertising a pump with an improved impeller, I have no idea if it’s worth the extra money but that’s something that may be worth a look.
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Ok, some reading found a CJ5 (F-head same block) with a similar situation of uphill or over 40MPH overheating. Three things came out of that conversation.
!) is thermostat in upside down? 2) with no heater, are there BY-PASS hoses on pump to block, or from pump to rear side of block for better circulation at speed or uphill load? 3) is there a blown head gasket?
Result for that guy after "trying it all" ended up being "the radiator". He replaced the radiator with a different used one and the problem went away. Just some food-crumbs for thought. Good Luck!
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Thanks for the replies.
In trying to recall the thermostat orientation, I'm not sure it's possible to put it in upside down. The spring and copper cylinder would hit the housing, I think. In any event, the spring is facing the block, and I've drilled the bleeder hole to allow bypass of water to prevent overheating from an air pocket.
No bypass hoses from rear of block to water pump.
No sign of a blown head gasket: no sign of water out the tailpipe, no sign of foam around oil filler tube, no bubbles in radiator while running, compression test is consistent across all 4 cylinders.
When I had the radiator serviced, the shop boiled, and flow tested. Much to my surprise, they stated it was in great shape - I'm sure it's been re-cored (maybe more than once over the past 75 years.
I've found a NOS bellows type thermostat and NOS waterpump. Those are on the way. If that doesn't work, a radiator may be in my future.
Aain, thanks for the feedback. I'll post after I change out the parts and test drive.
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So, it's been a while, to say the least. Here's where I am:
Replaced thermostat to new 160, replaced water pump, flushed radiator, tried various timing settings using vacuum, dwell, and rpm. Nothing worked in terms of getting rid of ping after engine heats to 200 going uphill. All very disappointing.
However, i may have stumbled upon a solution. Problem is, I don't know what the downside to doing what I'm doing is, if there is one. One of the ways the effects of eliminating lead was offset was by introducing octane in gas. Given that, I set the timing back to what ran the best and filled the tank with 91 octane without ethanol. Since doing so, I've not heard pinging even though the temps run at 200 at times. I tried backing off to 87 octane with ethanol (I cannot buy 87 w/o octane) and the pinging returned, although not very often. The problem is that I don't know if the pinging was because the octane level was lower or because it contained ethanol. Because I cannot buy ethanol free 87 octane, I have no way to prove out either scenario.
So, for now, it's ethanol free 94 octane.
One other very disturbing problem occurred while testing all of this. At one point, the engine started skipping and coughing like there was no tomorrow. With all the changes to timing, gas mixtures, octane levels, etc., I thought for sure I'd done permanent damage of some sort. I checked for spark at all cylinders, pulled plugs and checked compression - all looked OK. As I was putting plugs back in, I noticed what you'll see in the attached image - one of the electrodes on the spark plug was completely gone. Disturbing as all hell!
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Non-ethanol at 94 octane? Ours here in south Florida is 90.
FYI... I lost a Champion spark plug core on my outboard once, and it blew the engine's piston into pieces which did even more damage.
You mention compression OK, but where did the piece of core end up? Probably, the Willys low compression design, left extra room for "parts" above the piston, unlike my high-performance high-top pistons in my outboard with "no space". RPM at occurrence probably also played a part.
Bottom line, that core is "somewhere", but where and what damage will it do later??? Good Luck!
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Wow! Yeah, that would affect performance.
On another thread octane/timing discussed. I've done a quick search about timing and apparently there is many experimenting with timing adjustments.
https://cj3apage.com/Forum/index.php?topic=5940.msg43189#msg43189
Once your spark plugs are sorted, in addition to octane tests, this may be an idea.
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PS... You may want to keep that core-less plug. It can be used to turn a cylinder into an "air-pump" if needed for a "road-side emergency" to inflate a tire... with some hose added of course.
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SteveKfl & Rus- Thanks for the response. No clue where the electrode ended up, but testing all 4 cyl for compression indicated with 5-7lbs. Not burning any oil, etc., so assuming it ended up getting spit out past the exhaust valve, but who knows. I'm just keeping my fingers crossed.
I might have the octane rating wrong but pretty sure it's 94. The whole issue is around the effects of ethanol (has a higher-octane rating of around 109) and the point of combustion of 9x octane w/o ethanol vs. 87 w/octane. To be honest I do not know if one would be better than the other. Since I have no markings, I don't know where i ended up in terms of timing before TDC. All i do know is that the pinging is gone with the 9x octane with the timing set for max vacuum and correct dwell and rpm. It was a hit or miss operation for a while, but it's finally running with plenty of power, still hits 200 - 210 temps but no pings, so this is where it'll stay.
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May I clarify something? Octane is not a component of gasoline but is the numerical measure of the amount of compression a given volume fuel can withstand prior to ignition. Higher octane ratings indicate fuel that is less likely to pre-ignite when under pressure, which can cause engine damage.
Timing and mixture are key contributors to engine performance. Pinging under load indicates either/both incorrect timing and/or a mixture that is too lean.
Also, timing that is too far advanced and/or a too lean mixture will contribute to overheating.
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my f head is .060 over and has never over heated. i do use the auto lite 295 plugs as they go deeper into the combustion camber. and thanks f to scout pilot for helping my set the carb up over the phone.
fyi, i just had my rad re cored last summer with a newer style set up ( it's now 2 core ) due to the radiator leaking and it runs even cooler then before. it wasn't cheap but looks great , and it's still old school