PDA

View Full Version : Truck makes clicking noise when engine is working hard?



kerlin
Jul. 11, 2012, 11:40 AM
The truck in question is a 1991 Chevy 3/4 ton, 130k miles, great shape and sees the mechanic regularly. It's fully kitted out for towing and really only driven to haul the trailer. It's got more than enough power even for the steel 2h bumper pull I haul. (In its previous life it hauled a fifth-wheel camper all around the Pacific Northwest.)

For quite some time now, it's made a sort of clicking noise when it's under a lot of stress - say a hot day, hauling the trailer with both horses up a hill on the highway. The noise only happens when I am accelerating, and only when I accelerate beyond a certain point. I can accelerate slowly and gently and not have the noise at all, or I can push the gas pedal harder and get it more quickly, but it almost always kicks in at higher stress, as in that above-mentioned hill, or higher speeds. No noise at all hauling on surface streets/locally.

There's no loss of power whatsoever, nothing to indicate *any* problems with the functioning of the truck, just that clicking. It's an even, steady click that goes a bit faster the harder I accelerate. It sounds a bit like sticking a baseball card in your bicycle spokes.

It's going in to the mechanic early next week, and I'm going to try to get video of the noise while hauling this weekend so he has evidence of it, but any ideas on what this might be? I'm trying to prepare myself just in case it needs a bigger bill than I am planning for...

prairiewind2
Jul. 11, 2012, 12:29 PM
Years ago, we had a Ford van that did the same thing. My dad - great mechanic! - told me what the problem was, though I can't remember now what he called it. Anyway, higher octane gasoline (premium gas) solved the problem.

If your truck is a diesel, though, I haven't got a clue!

Liz

Appsolute
Jul. 11, 2012, 12:39 PM
"Knocking" - It can be from a number of sources, and something that you DO want to get checked out right away, as it can be a sign of more serious problems - or as simple as gas with too low of an octane.

It can be from bad sensors / air fuel mix being off, issues with timing, cooling issues, fuel injection issues, the list goes on.

Usually it is caused by the fuel combusting in the piston chamber from pressure, rather than the ignition spark – creating a knocking sound. There are different things that can cause this. Your mechanic should be able to locate the cause, and be very familiar with engine knocking.

Frank B
Jul. 11, 2012, 03:42 PM
Another possible cause is one or more loose bolts on the exhaust manifold(s).

I had a '66 Mustang that came from the factory this way. The mechanic loosened all the manifold bolts and re-tightened them in the proper sequence, after replacing one of the gaskets.

Equibrit
Jul. 11, 2012, 04:55 PM
Tappets AKA valve lifters.

AliO
Jul. 11, 2012, 07:02 PM
Sounds like lifters to me too.

ReSomething
Jul. 11, 2012, 07:24 PM
Ticks are lifters. Knocks can be timing and a few other things.

I started off to work once and got a little bit of a knock 10 miles out. Rather than abort I kept going and at 30 miles the head gasket blew and I limped in to work half an hour late. Mind you, that knock was terminal and not much I could have done except delay the inevitable. Take it in to a trusted mechanic.

Guilherme
Jul. 11, 2012, 07:43 PM
This noise can mean multiple things, some minor and some major.

One cheap and easy fix of a minor problem is to change the in-line fuel filter. They are cheap and easy to get at a local auto parts store. If you don't get adequate fuel flow at high power you might lose power as well as get the noise but sometimes you just get the noise.

Better fuel quality can also solve the problem (assuming you can get the fuel the engine). This will cost more than the filter but you might not have to use the higher octane for daily driving.

If these don't work you likely have a more serious problem and will require professional help.

G.

RAyers
Jul. 12, 2012, 01:32 AM
What engine do you have?

The 454s (g-d love those engines) were notorious for overheating the exhaust manifold by the #8 cylinder resulting in a tapping noise under heavy load. I always was wondering when I heard it on my old truck. New gasket and resurfacing was the fix. I just kept driving. Put a better exhaust system and rerouted the fuel lines.

kerlin
Jul. 12, 2012, 09:00 AM
Thank you for all your suggestions! It's definitely going to the mechanic for a full lookover in a few days. I'm afraid I'm not exactly sure which engine I have, but I will check.

I've done some searching, and there are a surprising number of videos on YouTube with engine ticking/knocking sounds. The closest to my truck's sound is this one: http://youtu.be/ZoRJkPcdgdY. But again, it only makes this sound under heavy load and while accelerating.

I'm happy to fill it up with a better octane fuel but I'm going to hold off on that until it sees the mechanic.

Fingers crossed it's just a valve problem and this isn't too much of a budget hit - I had a couple of vet bills last month and was hoping to get out of the summer without writing any more huge checks...

AliO
Jul. 12, 2012, 11:52 AM
Thank you for all your suggestions! It's definitely going to the mechanic for a full lookover in a few days. I'm afraid I'm not exactly sure which engine I have, but I will check.

I've done some searching, and there are a surprising number of videos on YouTube with engine ticking/knocking sounds. The closest to my truck's sound is this one: http://youtu.be/ZoRJkPcdgdY. But again, it only makes this sound under heavy load and while accelerating.

I'm happy to fill it up with a better octane fuel but I'm going to hold off on that until it sees the mechanic.

Fingers crossed it's just a valve problem and this isn't too much of a budget hit - I had a couple of vet bills last month and was hoping to get out of the summer without writing any more huge checks...

That sounds like an exhaust leak by the manifold. A leak would happen all the time, so that's probably not your issue.