starter and oil pressure issue :(

[travisr1988]

Ok, so my 79 c20 with a 350 is giving me oil pressure issues once again. It used to do this when it was hot out, same with the starter not working at all for 10-15 minutes when parked for less than 30 minutes after driving alot in the heat. However I changed the oil/filter, did alot of work to the motor (tune up, newish dizzy, timing set, rebuilt carb, new tstat, air filter, battery, cables, starter solenoid) and it stopped giving me trouble. Now that it's getting hot again the issues came back. So far the starter issue only happened once since the heat rolled in, the oil pressure issue occurs everytime I start the truck when it's hot out and the truck is still warm, even if just barely above the very first mark on temp gauge.


Issue #1: After driving on hot days alot the truck will not even attempt to start, turn the key radio lights, everthing else works fine, truck just won't even try turning over, no clicking, nothing at all. after I let it sit for 10-15 minutes it'll start right up.

Issue #2: My more worrisome issue; When it is hot out and the truck has not fully cooled off (temp gauge reads anything other than dead bottom) I get no oil pressure. If I rev the engine for a few seconds I get oil pressure (up to probably 2000-2500 rpm for 5-10 seconds) After that it runs great.

What should I check or replace to resolve these issues?

 

[robert8096]

The first issue sounds like starter heat soak or a loose ground or power wire but my money is on the heat soak. How old is the starter?

On the second issue is that a factory oil pressure gauge or aftermarket? Are you saying that the truck has pressure when cold and once it warms up it has none unless your rev the engine? If factory gauge it could be the sending unit. It could also be that the engine is worn out and when warm the bearing clearances are too great and cause the loss of oil pressure. Need more info.

 

[travisr1988]

The first issue sounds like starter heat soak or a loose ground or power wire but my money is on the heat soak. How old is the starter?

On the second issue is that a factory oil pressure gauge or aftermarket? Are you saying that the truck has pressure when cold and once it warms up it has none unless your rev the engine? If factory gauge it could be the sending unit. It could also be that the engine is worn out and when warm the bearing clearances are too great and cause the loss of oil pressure. Need more info.

Hot or cold I have oil pressure, except when I start it warm. If I start it cold it doesn't lose pressure when it gets warm. If I start it warm it gets 0psi until I rev it.

It is a factory gauge. I suspect the engine is going out soon as it doesn't seem to run the same consistantly, I mean the weather makes a huge difference in mileage, smoothness, sound, power, etc. And today I revved it a little after it stumbled backing into a parking spot on a very slight slope and it blew white smoke (coworker informed me of the smoke). It immediately smelled like unburned gas if that makes any difference. The carburetor was recently tuned for best idle quality and vacuum.

 

[travisr1988]

The first issue sounds like starter heat soak or a loose ground or power wire but my money is on the heat soak. How old is the starter?

On the second issue is that a factory oil pressure gauge or aftermarket? Are you saying that the truck has pressure when cold and once it warms up it has none unless your rev the engine? If factory gauge it could be the sending unit. It could also be that the engine is worn out and when warm the bearing clearances are too great and cause the loss of oil pressure. Need more info.

Starter- I believe it is original, solenoid was replaced with a new one about nine months ago. original solenoid crumbled when I touched it. Wires are all good and tight. probably heat soak, my dad mentioned that before.

Hot or cold I have oil pressure, except when I start it warm. If I start it cold it doesn't lose pressure when it gets warm. If I start it warm it gets 0psi until I rev it.

It is a factory gauge. I suspect the engine is going out soon as it doesn't seem to run the same consistantly, I mean the weather makes a huge difference in mileage, smoothness, sound, power, etc. And today I revved it a little after it stumbled backing into a parking spot on a very slight slope and it blew white smoke (coworker informed me of the smoke). It immediately smelled like unburned gas if that makes any difference. The carburetor was recently tuned for best idle quality and vacuum.

 

[89Suburban]

 

[chengny]

Replace both battery cables. They can look like brand new from the outside and be rotten dust under the sheathing. If the starter is known good and the battery is okay - the only thing left in that circuit is the cabling.

The negative is easy- battery straight across to the alternator mounting bracket or wherever.

On the hot wire to the starter/solenoid pack use the old wire to pull the new one through the space between the frame and engine. It's a sucky job if you do it correctly but this makes it easier:

Be aware, there is a wire clamp for that cable buried down buy the gas pump. Other than that, cut the battery clamp off the old wire and tie or tape the starter end of the new one to it and pull it through.

Oil pressure.... lots of possible causes for low oil pressure. I know you have a gauge but this describes the warning light:

If the warning light remains lit when it normally should be out, replace the engine unit before proceeding further to determine the cause for a low pressure indication.
The warning light will sometimes light up or flicker when the engine is idling, even though the oil pressure is adequate. However, the light should go out when the engine speed is increased.

And that switch closes at only 10 psi. My point is; the journal bearings in engines don't require 45-60 psi. They develop their own pressure internally due to the rolling motion of the journal through the bearing shell.



You have a 4WD truck. It's an afternoon job to drop the pan and replace the oil pump. And they are only like $50.

White smoke from the tail pipe is another story. That's bad medicine- unfortunately almost always means a HG is gone.

 

[MrMarty51]

Pipe T that oil pressure sending unit and install another guage,hook both guages and compare between the two.

 

[travisr1988]

Replace both battery cables. They can look like brand new from the outside and be rotten dust under the sheathing. If the starter is known good and the battery is okay - the only thing left in that circuit is the cabling.

The negative is easy- battery straight across to the alternator mounting bracket or wherever.

On the hot wire to the starter/solenoid pack use the old wire to pull the new one through the space between the frame and engine. It's a sucky job if you do it correctly but this makes it easier:

Be aware, there is a wire clamp for that cable buried down buy the gas pump. Other than that, cut the battery clamp off the old wire and tie or tape the starter end of the new one to it and pull it through.

Oil pressure.... lots of possible causes for low oil pressure. I know you have a gauge but this describes the warning light:

If the warning light remains lit when it normally should be out, replace the engine unit before proceeding further to determine the cause for a low pressure indication.
The warning light will sometimes light up or flicker when the engine is idling, even though the oil pressure is adequate. However, the light should go out when the engine speed is increased.

And that switch closes at only 10 psi. My point is; the journal bearings in engines don't require 45-60 psi. They develop their own pressure internally due to the rolling motion of the journal through the bearing shell.



You have a 4WD truck. It's an afternoon job to drop the pan and replace the oil pump. And they are only like $50.

White smoke from the tail pipe is another story. That's bad medicine- unfortunately almost always means a HG is gone.

Both cables have been replaced, solenoid and battery have also been replaced. I keep hearing "heatsoak" from alot of guys at the local meet, some said wrap with a heat shield and it won't have any more issues.

The oil pressure- I have no light, just the gauge. Also my truck is 2wd hence the reason it says C20. And low oil pressure doesn't bother me so much as it's supposed to be 10psi per 1000rpm, so idle should have about 7psi, it's NO oil pressure that concerns me, to be honest I'm afraid to dig into this motor as the previous persons who worked on it put the wrong bolt in the crank, so I fear more than that got messed up. And quite frankly I can't afford a new engine yet. As for the smoke, I asked my coworker who let me know about it if he was sure it was white and he replied "I really can't say for sure, it was just a little puff, it could have been light gray or light blue" which makes more sense as my oil is not muddy and I have not found any other indicators of a blown head gasket, and I know my truck burns a little oil, sometimes enough to smell in the cab. Oh, Related to the cooling system, my truck has only gotten above 170* once since I've owned it and that was when it was very low on coolant (leaking tstat housing, tried to fix, but still leaks just not as bad). I replaced the tstat with a 195* unit as that is what it calls for, but it never gets past around the first mark (155*) On a really hot day and driving all day in traffic it'll get to about 170* but thats it. Is that am issue or should I not worry about it?

 

[HotRodPC]

DO you have headers on this motor? Is the header crowding the starter if it has them? Does the solenoid have a heat shield on it??? My 84 C20 starter has a heat shield over the solenoid. I left it off with a starter change. Come summer time, I realized I needed it. Put it back on, problem solved.

 

[travisr1988]

DO you have headers on this motor? Is the header crowding the starter if it has them? Does the solenoid have a heat shield on it??? My 84 C20 starter has a heat shield over the solenoid. I left it off with a starter change. Come summer time, I realized I needed it. Put it back on, problem solved.

No headers, never had a heatshield that I know of. Maybe I need to get one from the junkyard sometime.

 

[HotRodPC]

It might help. IIRC, it just has 2 spring type clamps on it, and you just clamp it over the solenoid and it deflects the heat off the exhaust manifold or headers.

But you might need to figure out why it's getting so hot. Are you running real lean causing your exhaust to run real hot maybe? How about a Cat Converter? Do you have one? Maybe it's clogging and causing your exhaust manifolds to get hotter than normal.

 

[travisr1988]

It might help. IIRC, it just has 2 spring type clamps on it, and you just clamp it over the solenoid and it deflects the heat off the exhaust manifold or headers.

But you might need to figure out why it's getting so hot. Are you running real lean causing your exhaust to run real hot maybe? How about a Cat Converter? Do you have one? Maybe it's clogging and causing your exhaust manifolds to get hotter than normal.

Hmm, I'll keeo an eye out.
No cats, factory manifolds. Tuned with vacuum gauge, would a lean mixture show symptoms?

 

[HotRodPC]

Hmm, I'll keeo an eye out.
No cats, factory manifolds. Tuned with vacuum gauge, would a lean mixture show symptoms?

Yes, you'd have symptoms if you were that lean to cause excessive heat. You'd likely be so lean it would be lean misfiring. If you tuned with a Vac Gauge and it's running good, that's not the issue either. No Cats is a good thing. So either of these is not likely the issue.

You're not having any vapor lock fuel issues at all either???

 

[travisr1988]

Yes, you'd have symptoms if you were that lean to cause excessive heat. You'd likely be so lean it would be lean misfiring. If you tuned with a Vac Gauge and it's running good, that's not the issue either. No Cats is a good thing. So either of these is not likely the issue.

You're not having any vapor lock fuel issues at all either???

How can I tell? I mean the truck does crank a little when I start it, sometimes atarts kn the first crank sometimes it takes a few seconds or cranking. Usually starts right up when warm, which is usually when I have to rev it to get oil pressure. Could I have a fuel issue when warm that keeps the idle to low? Carb was tuned with vacuum gauge for highest vacuum at idle (750rpm I believe) while it was fully warmed up (or as warm Aas it ever gets).

 

[robert8096]

I suggest you get a aftermarket oil and temp gauge setup. The oil promblem your describing sounds really weird. If you put a 195 stat in and the gauge never gets above that reading it would mean that the stat never opens and you are not getting water flow thru the engine which I highly doubt. Oil issue could be the pump but I suggest the aftermarket gauges to see what really is going on.