I'm getting really pissed right about now.....

[chevychic]

My truck is being a PITA again. We had a really good summer, no problems. We went to the mountains, the lakes, and took many long drives together.
Last week I posted about it running rough again on the freeway and was thinking with the colder weather maybe there was some relation. I also thought it might have something to do with the fact I was driving my truck at about 80 mph when normally I stay between 65 and 70. When this happened at the beginning of the year, the problem was suggested, then tracked down to be distributor related. (Even took it to a shop first to have them run a diagnostic on the engine...they suggested the problem was coil related) Replaced the distributor...it ran like a charm.
Now it's doing it again, but with a couple things different. So I'm thinking my problem could have been 2 problems.

Yesterday I had to drive out to another town. After about 20 min on the freeway at my normal 65 mph it starts running really rough. The feeling was like being on a rough road or the tires were unbalanced, lot's of vibration. If I let off the accelerator or didn't try to accelerate more, it wasn't that bad. If I tried to accelerate, it got really bad...lot's of vibration. When I stopped, it idled fine (when this problem arose earlier this year, it would miss badly when it tidled). If I revved the engine, it would sputter a bit as it was revving.
I ended up taking country roads instead of the freeway to get to where I needed to go and home again. It did ok as long as I didn't get on it. But on the way home, about a block or two from my house, I start hearing a whining coming from the engine. As I accelerate it got louder. It almost sounded like the turbo on my husband's GSX but I'm pretty sure no one snuck up and installed a turbo on my truck while I was out
The sound continued after I got home and let it idle. Got out and checked the belts to make sure everything was as it should be and all was good.
Later that night I went out to see if it would make the sound again but it didn't. I didn't try to drive it though.
One thing I did notice when I looked at the engine was a bit of oil that is splattering out over the driverside valve cover. It's coming out of the filler hole and also seems that I need to replace the valve cover gasket. I have no idea if this is related to anything that happened while I was driving but thought it might be worth mentioning.

So, I'm wondering if I have 2 problems.....

Someone mentioned on my post earlier that the rough running could be a problem with fuel delivery. I'm planning on replacing the fuel filter and was wondering if it might be worth replacing the fuel lines as well. They seem kind of old and I figured it wouldn't hurt, but what are your opinions/suggestions?
As far as the carb goes, it's a Q-jet rebuilt last December. It doesn't have the fuel filter in it, in fact I discovered it missing so added one inline between the fuel pump and carb.
Moisture getting into the cap was also suggested but this week has been pretty nice, no rain and not much moisture at night.

The thing that has me confused is why it ran great all summer, taking long trips often at freeway speeds, but now all of a sudden it's running badly. I took a break from doing new things to my engine all summer so there's no way I could've messed something up.

As far as the whine goes....I'm totally lost. I couldn't pinpoint where the sound was coming from and have no way of knowing if the two problems are related.

Help?

[MSL]

Have you noticed any over heating at all. Also take and smell the oil dipstick and see if there is alot of fuel smell. as for the fuel problem that could ber a very good possibility how old is the fuel pump.? Also take a timing light and watch your timing mark with the advandce disconnected and rev it a little while watching and let go is the timing mark bouncing around if so maybe a timing chain. I know i redid my timing chain because i was having similar problems but not as bad as yours and that worked. There could be alot of possibilites going on as for the whinning part. That could be a seal,bearing torq convertor is it low check that and check all lines vacum. only way to help is to be there and hear it. hope this will get you started.

[old Rusty C10]

the moisture in the cap i was suggesting was due to temperature changes, condensation if ya will in the cap. it seems that your idling problem could also be related to the fuel filter/delivery but i dont think you would need to change the lines; the usually dont go bad unless ya have alot of salty roads in the winter and all and youll see pitting on the outside before ya have problems on the inside a gas filter is a pretty cheap guess and if its been a while since ya chaged it ,it wont hurt to change it. I would also check the top of your rotor and the spring thing in the cap that could cause electric problems like youre saying also crud ont he rotor /cap
as for the whining could oil have gotten onto your belts causeing some kind of slippage or noise id warm the truck up good to see if it comes back keep us informed hope i helped some

[79Silv4x4]

Vibration and such under load could mean bad plug wire(s). Not sure, but just something else to consider.

[Tom]

Vibration under load makes me think detonation or poor running. Check for vaccum leaks and timing. Don't replace the fuel lines, at least not the metal ones. They don't really go bad. Rubber line should be replaced. Replace the fuel filter and make sure your getting good pressure from the pump.

Remember all the problems I was having heather? It was a vaccum leak that fixed itself

[78SilveradoSWB]

You might have some water in your fuel tank from condensation or just bad gas from ARCO or some other low cost gas station. Don't forget, gas stations in Oregon start putting that oxygenated stuff in the gas during the fall and winter months and too make the vehicles run rough too. Try putting some fuel additives that eliminates moisture in the fuel system.

[ElGracho]

Heather,

I've been going through similar problems recently on my 84. It was a clogged fuel pickup in one of my tanks. Check if switching tanks makes a difference.

I would also replace all of the rubber line under the hood and your fuel filter. This would be inexpensive and would rule out that as a potential problem.

Other possibilities would be the fuel pump and even a bad tank switching valve. I've had a tank valve get hung up in mid position and still allow the truck to run but starve it of fuel. A telltale sign of that on an 81-86 truck is the fuel gage pegging high.

[swervin ervin]

I was thinking vacuum leak. The oil on the valve cover could be caused by a bad PCV valve. Of course all the above suggestions are great ones too.

Things like this are hard to diagnois over the net. These are the kind of things you need to see/hear in person.

[Bowed]

It Idles OK but vibrates under load and can wine like a turbo under load . Do you have a clutch type fan ?

[chevychic]

Originally posted by Bowed
It Idles OK but vibrates under load and can wine like a turbo under load . Do you have a clutch type fan ?

Ummmm...I'm not exactly sure if I have a clutch type fan. If this is a clutch fan, then yes, that's what I have



The whine was during idle as well as while I was driving, but that didn't start happening until I was almost home. I think Bob might be right and I might have oil on the belts causing the noise.

Tom and Mike, I considered a vacuum leak, but I didn't think those come and go like this has. When this happened last year, I checked but couldn't find one. Although I didn't have the best tools to determine for sure.

Mike, I do have some seapage coming out of the PCV valve that I also noticed yesterday and plan on replacing. Would it matter that my PCV valve is on the passenger side when the oil splatter is on the drivers side?


The bad gas could definitely be something, but I thought they didn't change the gas until November. Although, I'll ask the guys down at the Chevron to be sure. I ONLY buy gas at Chevron.

I do plan on changing all rubber fuel lines and replacing the metal line between the pump and the carb since mine broke in December and I replaced it with a rubber line. This problem started happening after that, so I figure it's one more thing I can eliminate.

I'll start with these things and then move onto the fuel pickup suggestion from Joe. I've never used the other tank because my switch doesn't like to work so I might as well replace it while I'm at it.

There are so many times when I wished I lived in an area where more of you are at so when I have problems like this, I can get some live help
I have one guy around here that I trust and he'd probably help me out and let me learn and watch, but this guy is, well you'd just have to understand him. He's a grouchy old man and knows his stuff but gives me a LOT of crap about having a lifted truck and doing my own work on it, and it being a Chevy . I can take a lot of crap from people and have a pretty thick skin and am even more determined to prove someone wrong, but he gives it out in such a way that would make me want to deck him or kick him in the shins and well, that's just not a good idea.

And I refuse to take it to a shop until I've exhausted myself because I won't learn anything if someone else fixes it for me.

So uh, any of you wanna come visit or move to southern Oregon?? It's beautiful, no hurricanes or tornadoes, no earthquakes, lots of lakes and rivers and big trees, and excellent fishing!! hahaha

[Russell]

Welcome to my world =/ My truck still hasn't run yet :P

Hopefully tommorow will be the day...

[1FaastC10]

Originally posted by chevychic
So uh, any of you wanna come visit or move to southern Oregon?? It's beautiful, no hurricanes or tornadoes, no earthquakes, lots of lakes and rivers and big trees, and excellent fishing!! hahaha

hmmm... sounds tempting. are you paying airfare?

[78SilveradoSWB]

Doesn't look like a clutch fan, picture too small for me to distinguish, but it looks more like one of those flexlite plastic fans. I had a clutch fan on my 78 454. Its metal with 7 blades and with a fin-like hub on the front, which I believe is the clutch mechanism.


Chevron is very good brand of gas. Not sure when the start date of the oxygenated gas, but still you might have water in your tanks and need some of that fuel deicer and some good carb cleaner like that Chevron product with Technoline.


Southern Oregon is pristine, but too darn close to California.
Loved the Gold Beach area and the Rogue River area though, but it gets better up north.

[mhorning]

I used to have a Bronco that did the same thing. I tried everything to fix it. Finally, I took a can of clear Krylon paint and painted everything electrical, the plug wires, coil, cap. It fixed the problem. Only thing I could figure was that some moisture had gotten into something. Good Luck.

Mike H

[MSL]

No that fan is a plastic flex fan the same one i have. Also if you need help let me know i live here and could give you some ideas. just let me know.

[stan79chevy]

check the plug wires. if you have headers it could have melted through one of them. also maybe the coil if its having problems at higher rpm's

[Lester]

You mentioned the engine misses above 65 mph. Happen to know if this is close to or above 4000 rpm?

The reason I ask is that an incorrectly grounded engine will cause an HEI to miss above 4,000 rpm nearly everytime you wind the engine higher than 4K.

Check the engine ground, its the un-insulated braided cable between the block and the cab usually on the passenger side of the engine. If this is missing or or loose or sitting in corrosion this will create ignition problems.

Oil on the valve cover opposite the PCV valve can be an indicator of an internal problem such as blow by, especially given your comment about it coming out where you add oil to the engine. If its not coming out of the dipstick tube its probably just the PVC valve stuck or the hose from the valve to the carb is plugged or collapsed. The PCV valve sucks fresh air through the engine from the opposite valve cover. If this is blocked or not working the oil shows up around the non-PCV breather hole in the other valave cover and around the oil filler plug or cap no matter which valve cover its in.

Also try snugging the bolts or nuts on your Qjet some, these work loose in the course of driving especially when the temp changes.

Don't change everything at once make a change and drive to try to isolate the problem for future reference.

Good luck.

Lester

[Blue Beard]

Check the rubber fuel line from the tank to the frame.

Mine developed a problem here that I couldn't find.