Mechanical issue with old truck

[bob208]

I have a 38,39,46, 2 69's 2 70's 2 72's 78,79. all chevy .that is what I mean by old trucks

[JWT]

cIf you believe aluminum doesn't rust or break down with salt water try taking a bare piece of aluminum and sitting it in a salt water solution.

Look at all the old aluminum Body By Fischer rocker moldings. With Michigan salt you can just about watch them disintegrate.

[am44mag]

I looked at a few things. I'm by no means a mechanic or someone who knows a lot about engines, but I know a little and can usually fix the issue if I can find it. A lot of what you guys are suggesting I'm having to google. The injectors look to be working properly. They're both spraying a mist. The fuel pump was replaced about 18 months ago, but I will see about checking the filter. I'll check the spark plug wires tonight after it gets dark. I'll check the belt too. I had to replace one on a 2008 Ford Fusion for my cousin a few weeks back, and this one looks 1000 times easier since it's nowhere near as cramped. I'll probably run by an auto parts place tomorrow and have them check for codes.

I appreciate all the advise fellas.

[abunaitoo]

Check the wires in the dark. If any are leaking, you'll hear and see it.
I've had to change a number of throttle body base gaskets in the past.
I think this truck has a electric EGR valve.
Sometimes a bit of carbon get's stuck in the seat.
Had that happen many times.
Just remove and pick the rock out.

[Lloyd Smale]

couple more possibilities is gm motors of that era are know to have the harmonic balancer go bad. They are mounted with rubber and the rubber gets old or slips. Could be causing your shake. Watch the balancer while its running to see if it wobbles. The tick could very well be an exhaust manifold gasket or the connection from the manifold to the exhaust. Look for carbon around them.

[drizler]

Well, my old truck is giving me fits. It's a 1995 Chevy C1500 Silverado V8 with about 132,000 miles on it. The power steering pressure hose gave out, but that looks to be an easy fix. The part is ordered and there is so much room in that engine bay that I can probably have it replaced in a few minutes.

That might not be the only issue though. It's doing what I can best describe as a shiver. It does it when it's worst when it's idling (occasionally it will stop for a second or two), it does it occasionally when you're accelerating, and it will do it a little (though a lot less roughly) when you have the cruise set at 70 mph. Something in the engine bay is also making a clicking sound. I'm not sure exactly what that is, but it's coming from around the area of the alternator (brand new, just replaced last year). It's like it's really having to fight for power.

The engine is not overheating, all the fluids except the power steering are good, and while a little rough, the truck is still drive-able and still starts up without a fight.

Any ideas?

The click is usually the AC doing its usual thing. It’s fairly loud . Shimmies n stutters pull the distributor cap. If it’s crappy lookin get a new one and rotor. If it’s not but it’s kind of dark just clean it up with some steel wool coat rotor too. Take a look at the pickup inside the distributor. If it’s all rusty clean or replace it. They do grow rust on GM motors and when it’s deep enough weirdness happens. Nobody ever checks or changes these anymore so they get nasty over time.
Don’t ever discount fuel pumps dying at any age with the GM. They’re not very well-made is about the best thing I can say about them besides it being cheap in more ways than one. If you can get your hand in a fuel pressure tester check it.
I can’t remember With your years the last of the throttle bodies or full fuel injection With the rail. The later ones with fuel injection have a lot of issues with the fuel pressure regulator going bad That one’s on the side of the valve cover gasket and all you do is pull the vacuum hose off both sides of it and see if it’s got any fuel leak then do the vacuum hose. If it is get a new one, it’s a very common failure. They’re cheap .



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[Petrol & Powder]

Well this thread only took 6 posts to turn into a Chevy v. Ford thing.


Texas, you received good marching orders. The fact that the engine is sort of "hunting" for the correct RPM's and the condition sometimes subsides, tells me that it's probably not something major. In addition to the above advice, I would look for a vacuum leak.

[Ford SD]

To check spark plug wires.. What I have done

In the dark with motor running

Use a plant mister with water ... Mist the engine compartment and look for the sparks

if you do this you can normaly hear when one or more wires short to ground

2nd on the worn timing chain

on mine if you were driving up a hill it was fine .. go over the top of the hill and it would stumbe when going down hill

[Hannibal]

If you can find a timing light you can connect it and if the timing is erratic, particularly at idle, the chain is most likely worn. Not sure if this still works on the newer stuff, but worked great on the older ones. By older I mean the stuff with a distributor instead of crank sensors.

[popper]

Bad plug/wires usually mess up under load. That said, you do replace the PS hose so where does that fluid go? TBI doesn't use a dashpot for return to idle so bubbles a little. Dumb computer set idle and MAP/O2 sensors. I did have a merc with the starter cable hitting the hot manifold. Would run the batery down on a foggy nite, otherwise OK. Little black tape solves that one. Then the fake computer controlled carb. Carbon from the vapor tank gets into the valve and she don't run, floods out.
My guess is like the guy doing touch&go while I was getting finger printed. Burbbles as he set the mixture wrong. Second pass he did better. Hey, 2 weeks from prints to LTC in pocket. Wow.

[abunaitoo]

couple more possibilities is gm motors of that era are know to have the harmonic balancer go bad. They are mounted with rubber and the rubber gets old or slips. Could be causing your shake. Watch the balancer while its running to see if it wobbles. The tick could very well be an exhaust manifold gasket or the connection from the manifold to the exhaust. Look for carbon around them.

Forgot about the balancer.
Replaced many of those.
Also had to change a few timing chain covers.

[EDG]

If that model still has a distributor it might be time for a new cap and rotor. When you have warm humid rainy days carbon tracks in the cap will provide a leak path for a spark miss. Cheap rotors can have a microscopic pin hole burned through them that does the same thing.

[lancem]

I would change the module in the distributor, it is a multi function device and would cause your problems. I currently drive two TBI Chevy trucks, both with over 250K on them, daily drivers both with few problems with them over the years. In my experience the distributor module is the one that can cause the strangest intermittent problems and not be bad bad. It is easy to change, just two screws once you take off the cap, just a pain because it is at the back of the engine. Rockauto lists the ignition control module for under $20, so not a lot to invest in.

[geezer56]

Check the temp sensor for mixture control. It causes the engine to think it is cold all the time, as in cold start. Fuels accordingly. Causes stumbles and mis-fires, and cnd even bog the engine down. If you replace the sensor, be sure to replace the connector as well.

[jsizemore]

Had to say it. It's a chevy!

My 93 1500 W/T 4.3L had 487K on the odometer when I parked it a few years ago. My buddies' 95 V8 got the tranny rebuilt and the shimmy went away....for a while. The overdrive solenoid didn't get replaced (actually the valve/piston) and was leaking and not fully engaging. It progresses to the point that it will start shifting in and out at highway speeds. A little pressure on the the brake pedal will make it go away. Cutting the brown wire on the tranny lead will make it go away but increases your gas station visits. Good transmission shop can stick it on the analyzer and tell you for sure.

[Wag]

My initial thought was fuel system problems. But if you're getting a good spray out of the injectors, it's probably not that. Nevertheless, the fuel pump can start to have problems intermittently before it finally bombs. Get under the hood and replace the fuel pump relay. Those dang things cause havoc. They're supposed to replace those when they replace the fuel pump but a lot of guys just don't which is a major failing. Yours might even have two of those relays for the fuel system. With that many miles, just replace them for peace of mind.

Fuel filter would have been my next bet but again, if you're getting a good injector spray, that might not be the problem.

--Wag--

[Geezer in NH]

About time for the throttle position sensor to also **** out. My 94 ate one every 75-80K

[woodbutcher]

RE:Harmonic balancer.Check as noted.ALL brands have problems at times with the elastomer between the main part of it and the outer rim.Know of a couple that failed at hiway speeds.Just about cleaned the whole front of the engine off.Most expensive to fix.
Good luck.Have fun.Be safe.
Leo

[Wag]

As a quick comment, I recently picked up a 1992 truck on the cheap. It was a few less miles than yours but ran poorly and shifted very harshly. Five minutes to check the codes and I had 3 sensor problems identified, each of which contributed to one or more of the symptoms. It cost $150 for those parts, plus my time to install those sensors. I then did overlooked maintenance which included replacing the original equipment plug wires, distributor cap, and rotor. Truck starts, runs, and now shifts fine.

Gussing wastes time and possibly costs money changing unneeded parts. Start with the smarts installed in the vehicle, and go from there.

This.

--Wag--

[EDG]

You still wind up guessing when there are intermittent problems like carbon tracks in a distributor cap.
The electronics can say you have a miss but it never can tell you where or why....