oh, and for the record... never Teflon tape on a sending unit, but pipe dope is ok....
CK5
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Cooling System Overhaul - Stumped and Frustrated
- Thread starter dhcomp
- Start date
Your system should have two sending units on the motor, 1 for the guage and another for the PCM. Look up ohm readings for each guage (they may be different) and measure each with a multimeter. You should be able to find a source that translates the ohm reading to a temperature.
Do the two senders report the same reading?
I am not 100% sure this is the correct table:
Do the two senders report the same reading?
I am not 100% sure this is the correct table:
Temperature Degrees Fahrenheit Resistance - Ohms
210 = 185
160 = 450
100 = 1,600
70 = 3,400
40 = 7,500
20 = 13,500
0 = 25,000160 = 450
100 = 1,600
70 = 3,400
40 = 7,500
20 = 13,500
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The gauge units are all 0-90 Ohm. Fuel, oil, coolant.
Good point on the testing...you ground the gauge it should peg well over hot. Open circuit should go well past cold. If it responds accurately, it's likely the gauge is working correctly, however as mentioned, that says nothing about accuracy. But the sending unit wire ground/open is an easy, quick, free test. If it fails that test, you know something besides (or along with) the sender is a problem.
This is one of the reasons I'm hard wiring my cluster...there are too many places at the cluster, let alone the whole circuit (and that's just for one gauge) for there to be connection issues that can cause issues like this. Dad just dealt with an "overheating" issue that was caused by bad cluster contact, and my high beam indicator light randomly decides when to work for the same reason.
Good point on the testing...you ground the gauge it should peg well over hot. Open circuit should go well past cold. If it responds accurately, it's likely the gauge is working correctly, however as mentioned, that says nothing about accuracy. But the sending unit wire ground/open is an easy, quick, free test. If it fails that test, you know something besides (or along with) the sender is a problem.
This is one of the reasons I'm hard wiring my cluster...there are too many places at the cluster, let alone the whole circuit (and that's just for one gauge) for there to be connection issues that can cause issues like this. Dad just dealt with an "overheating" issue that was caused by bad cluster contact, and my high beam indicator light randomly decides when to work for the same reason.
Picked up an aux temp gauge to hookup.
Is there somewhere else i can put a temp probe on a standard 350? Woudl sure like to run the computer sensor (intake manifold), gauge sensor (drivers side head), and a 3rd aux temp probe to check gauge accuracy.
Is there a port on the passenger side anywhere?
How bad of an idea is it to run one in the water pump? I'd guess the probes are too deep for that connection.
Going to swap to the aux temp gauge tonight, and see what i can find out tomorrow. I swear, haha.
Is there somewhere else i can put a temp probe on a standard 350? Woudl sure like to run the computer sensor (intake manifold), gauge sensor (drivers side head), and a 3rd aux temp probe to check gauge accuracy.
Is there a port on the passenger side anywhere?
How bad of an idea is it to run one in the water pump? I'd guess the probes are too deep for that connection.
Going to swap to the aux temp gauge tonight, and see what i can find out tomorrow. I swear, haha.
Passenger side head has the same location for a sending unit as the drivers side head, since the heads are interchangeable. 
I'd stay out of the water pump, that's the "inlet" side, and while it would be useful to see what the radiator efficiency was, not where I'd want to be looking for your issue. Not sure how much clearance they have between the ports and impeller.
I'd stay out of the water pump, that's the "inlet" side, and while it would be useful to see what the radiator efficiency was, not where I'd want to be looking for your issue. Not sure how much clearance they have between the ports and impeller.
watch yourself trying to get that other plug out... when those pipe plugs have been in that long, they can be a real bear to get out...
if so, just change out your stock one for the new sender, and run the new gauge to it, even temporarily with the wire out from under the hood and coming in thru the window and the gauge laying on the dash.....
you don't need triple simultaneous verification of engine temp... you know what the old one said, see if the new is dif..
if so, just change out your stock one for the new sender, and run the new gauge to it, even temporarily with the wire out from under the hood and coming in thru the window and the gauge laying on the dash.....
you don't need triple simultaneous verification of engine temp... you know what the old one said, see if the new is dif..
Come on, you can never have enough gauges and sending units!
there's gotta be a Google image for a "multi-tee-d pipe fitting nightmare" on Google....
wait a minute...
dammit, the spellings probably wrong........
wait a minute...
dammit, the spellings probably wrong........
With at least a couple more gauges, I don't see a problem there.
remember who your talking to, i'm a marine mechanic... it's NPT HEAVEN! 
dual stations, alarms, fire systems, cooling, seawater, piss/poop, I've got more plumbing and senders in my daily joy joy than most.. 
trust me, I've seen plenty from homebrew boat owners, and sadly designer/engineers too.. "a boats worst enemy, is usually it's owner" is usually a good bet tho.. poor design, production, or prior plumbing/maintenence moron are always somewhere in the mix......
dual stations, alarms, fire systems, cooling, seawater, piss/poop, I've got more plumbing and senders in my daily joy joy than most..
trust me, I've seen plenty from homebrew boat owners, and sadly designer/engineers too.. "a boats worst enemy, is usually it's owner" is usually a good bet tho.. poor design, production, or prior plumbing/maintenence moron are always somewhere in the mix......
trust me, I've seen plenty from homebrew boat owners, and sadly designer/engineers too.. "a boats worst enemy, is usually it's owner" is usually a good bet tho.. poor design, production, or prior plumbing/maintenence moron are always somewhere in the mix......
I caught my roommate running heater lines on his FJ with brazed copper lines
Hard mounted to the motor too....
worst I see is car heater hose as saltwater intakes... that sh*t get's eaten/bloated/scary for some reason... well, that and electrical, I've seen more eyelits hooked to batteries than my subconcious can remember/scream...
Not even PVC? He doesn't have a clue, does he?
I'm beginning to think that what I do may be thought of the same way though...
I'm beginning to think that what I do may be thought of the same way though...
Not even PVC? He doesn't have a clue, does he?
He's normally better than that. Good thing i caught him on that one though. Must not have been drinking enough beer.
Not even PVC? He doesn't have a clue, does he?
I'm beginning to think that what I do may be thought of the same way though...
keep in mind... i'm talking off a seacock valve on the bottom of a boat, feeding saltwater to SOME system, wether that's a vibrating engine, ac pump, yada, you will generally have a flexible connection somewhere.. but it's an AC 95% of the time... sometimes a livewell or something...
in other words, giant 12 cylinder twin turbo Detroits (worked on a pair today, cowinkydinckly) will be fed by a 40lb bronze seacock valve that costs about a $G$, with a 5" x3' CG certified hose w/wire to it's raw pump, merrily on it's way, fill a 5 gal bucket in about 5.2 seconds....
most systems that take seawater in thru the bottom of a boat, will be a valve, flexible hose of some sort.. even an IO to some extent..rigid PVC has it's place, but those are usually fixed, anchored to bulkhead type systems.. water, toilet, central vac, etc... tons of copper for yrs in freshwater systems... 60's, 70's and even some 80's and current trawlers/builders run it for water systems.... tho you better know what your doing winterizing a 55' Grand Banks...
most production boats are into fancier, semi-rigid, PVC, etc, based plastics/hose these days for water systems, AC, etc...
butt the majority of NPT components you'll see are bronze.. pipes on motors, elbows, valves, etc... those Detroit valves would probably scrap for $75 to 100 in bronze.....
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So, the gauge i picked up isn't electronic. Oh well.
Tried the plug on the passenger side head, and got it out with zero effort. Thanks new motor
Anyone know the size, so i can replace it when this test is over? No idea where it fell to.
So, ran the gauge up onto the windshield wiper. Will drive it on the freeway to work tomorrow, and tow with it on Saturday.
We shall see how it does, although this gauge won't react nearly as fast.
Tried the plug on the passenger side head, and got it out with zero effort. Thanks new motor
Anyone know the size, so i can replace it when this test is over? No idea where it fell to.
So, ran the gauge up onto the windshield wiper. Will drive it on the freeway to work tomorrow, and tow with it on Saturday.
We shall see how it does, although this gauge won't react nearly as fast.
y5mgisi
1 ton status
Good luck!
Well, i take back every assumption i made about this manual gauge not working quickly.
First, it DID show my tstat opening late, with the temp up to about 220 before it dropped. 195˚ Stat.
Then, stop and go traffic, some freeway cruising, and my temp was anywhere from 195 to 210, with a quick stint up to 220. Wtf. What is standard variation? I'd think there would be very little, especially under low load. Yes, the factory gauge may be dummed down to not show changes this quickly, but i would think it would stay more consistent.
So, I'll tow with it on Saturday, and see what happens. But with this new knowledge, i'd think that my factory gauge was reading more or less accurate.
Keep in mind, i left my old temp probe in the stock location, and put this new gauge sending unit in the passenger side head. I'll swap the new temp probe i bought into the stock location tonight, but seems like an unnecessary step.
First, it DID show my tstat opening late, with the temp up to about 220 before it dropped. 195˚ Stat.
Then, stop and go traffic, some freeway cruising, and my temp was anywhere from 195 to 210, with a quick stint up to 220. Wtf. What is standard variation? I'd think there would be very little, especially under low load. Yes, the factory gauge may be dummed down to not show changes this quickly, but i would think it would stay more consistent.
So, I'll tow with it on Saturday, and see what happens. But with this new knowledge, i'd think that my factory gauge was reading more or less accurate.
Keep in mind, i left my old temp probe in the stock location, and put this new gauge sending unit in the passenger side head. I'll swap the new temp probe i bought into the stock location tonight, but seems like an unnecessary step.
220* is high to me. It's not high as in dangerous, it's high as in all new cooling system components with no load while cruising shouldn't be getting that hot.
With thermostat variations being what they are, 210* I would not consider outside the realm of normal, but 220* is too much IMO. That is what GM set the early electric fans to come on at, and since your mechanical comes on lower than that, something is up.
When did you hit 220*? Cruising with essentially no load? If it were me, I'd pull the thermostat and drive it if so. Stop and go is too hard to replicate a problem as odd as yours. As far as I'm concerned you've verified the temp spikes are real, and that your gauges are if not accurate, repeatable and indicating a change. With so many new parts that have to be assumed to be good (radiator, pump, motor, hoses) the thermostat is the one part that is known to be iffy out of the box.
If the temp spike is anything other than the thermostat, it will be there whatever the engine temp, which SHOULD be well under 195* with no thermostat if your cooling system is more than adequate for the load you are putting on it.
I suppose if you REALLY wanted to get anal about diagnosis with the thermostat out, you could cover more and more of the radiator with cardboard until you got the cruising temp to around 195* and see if it starts spiking again, but that would require some extremely tight control of your driving tests and I think probably unnecessary. With no thermostat, coolant flow can't be interrupted unless there is a hose problem, or something floating around somewhere that can plug a major passage, which is more than unlikely.
With thermostat variations being what they are, 210* I would not consider outside the realm of normal, but 220* is too much IMO. That is what GM set the early electric fans to come on at, and since your mechanical comes on lower than that, something is up.
When did you hit 220*? Cruising with essentially no load? If it were me, I'd pull the thermostat and drive it if so. Stop and go is too hard to replicate a problem as odd as yours. As far as I'm concerned you've verified the temp spikes are real, and that your gauges are if not accurate, repeatable and indicating a change. With so many new parts that have to be assumed to be good (radiator, pump, motor, hoses) the thermostat is the one part that is known to be iffy out of the box.
If the temp spike is anything other than the thermostat, it will be there whatever the engine temp, which SHOULD be well under 195* with no thermostat if your cooling system is more than adequate for the load you are putting on it.
I suppose if you REALLY wanted to get anal about diagnosis with the thermostat out, you could cover more and more of the radiator with cardboard until you got the cruising temp to around 195* and see if it starts spiking again, but that would require some extremely tight control of your driving tests and I think probably unnecessary. With no thermostat, coolant flow can't be interrupted unless there is a hose problem, or something floating around somewhere that can plug a major passage, which is more than unlikely.
The 220 spike was once before the tstat opened, and one more time after that.
I was doing about 45, slowing down to a stop, and noticed it was spiking again.
No real reason.
I boiled this Tstat before I installed it, and its at least the 2nd or 3rd since i've been having this problem. Crazy to say, but the problem as repeated with at least this tstat, and one other. WTF.
Wonder if a passage is blocked in this radiator.....
I was doing about 45, slowing down to a stop, and noticed it was spiking again.
No real reason.
I boiled this Tstat before I installed it, and its at least the 2nd or 3rd since i've been having this problem. Crazy to say, but the problem as repeated with at least this tstat, and one other. WTF.
Wonder if a passage is blocked in this radiator.....
