The Dreaded Rattle

[Wolfie_85]

Alright, I will be getting a 94 Explorer XLT from my dad, but I noticed that it has the "rattling" noise under load that some say involves valve work. It only does it up hills or accelerating at highway speeds.

Now to what people have said: heat sheilds (oh GOD yes let it be this! So cheap and easy!), rocker arms, MAF (really? Seriously asking, could the MAF cause this?) and last but not least, "run it with Premium fuel!"

So guys, let's cut to the chase; what is it, most likely? I don't like the sound of valve work. It means a trip to the shop, as I don't currently have the right tools, and live in an apartment that wouldn't take kindly to me having a project that intense happening in their lot. If i was to have a shop do it, how much do you think it would cost? Never worked on these engines. Up to this point, I had GM's (sorry. That's just how it worked out!)

I want to keep this thing on the road and running a long time. I always liked it and dad left it to me. Besides the rattle, by the way, it's in awesome shape.

 

[natenkiki2004]

If it's pinging/knocking with load going uphill, instead of trying to run premium fuel (which will help but isn't very immediate in terms of results), poke around the passenger side under the hood, close to the firewall. You should find some connectors, namely the EEC test connector and a couple others. You should find 2 wires with a grey plug in the end, like this:

That is often called the SPOUT connector, timing shunt, octane shorting bar or something else. I believe it will prevent computerized advancing of your timing. Removing it will retard timing and help with pre-ignition. (It was originally used for setting timing on distributor engines. I think it's a left-over tidbit in the harness for Explorers as there's no practical use for it aside from retarding timing which you shouldn't really use.)

If the grey plug is already removed then someone else applied this "fix". If it's still there, remove it and go drive your Ex. If the sound is gone then your problem is pinging/knocking from pre-ignition. This is a very common issue and while removing the plug often solves it, it can also remove power and decrease mileage. If this is indeed your problem, my advice would be to pop the plug back in, run the tank down and fill it up with premium (preferably ethanol-free).

That's what I've done with mine and mileage jumped 2-3MPG and I don't have pinging.


With all that said, it could easily be something else. Maybe you can describe the sound more or get a video of it?

 

[Wolfie_85]

Thanks, Natenkiki. Advice I didnt hear yet is always good! I don't have the vehicle in my possession just yet. It's still in another state, or I would record it! It's sort of a rattle. Kinda like nails in a can. Could very well be ping or knock. But only under certain conditions (highway speed if you accelerate or up a steep hill). It doesn't appear to hinder power or reliability. It drives great.

When I get it, I will try your fix!

 

[natenkiki2004]

I think only severe pinging will hinder performance where as light pinging will just be heard but still potentially detrimental.

The pinging I've heard is more of a spray paint can in another room being shaken randomly. Faint but distinct.

For what it's worth, I've done a fair amount of research and common valvetrain noise doesn't exhibit itself under load when warm, it tends to be more when the engine is cold.

I could be wrong or barking up the wrong tree, just trying to get you thinking about possibilities until there's more info or someone more knowledgeable comes along

 

[littlebro294]

Honestly you would be surprised on the noises the MAF sensor can make your engine make when its not running right, i had a ping type noise when i got on it even the slightest bit. I thought it was the cat going out it sounded so bad. Clean the MAF sensor and havent heard the noise since, but i do need to get a new one sooner or later haha.

 

[Gios]

rattle problem

I had the same dreaded rattle problem with my '93 XLT and ran about in circles trying to decipher the problem. I spent money on: premium fuel, MAF cleaner, 3M Fuel System cleaner, etc. No matter what, I would still get the rattle under load, like climbing a hill or even a strong head-wind.

Ultimately, I discovered my particular rattle problem was solved when I changed the plugs and noticed one was not fully 'seated' properly. When pulled, this particular plug had shown an unusual and distinguishable sign of fouling compared to the other five which burned normally. Also, it was noticeable that the new plug sank into the sock deeper than the previous plug was set.

After the new plugs had been installed (since about 5,000 miles now), no more rattle under heavy load conditions... Its got ~349,000 miles and rumbles (almost) as good as the day it left the lot.

 

[acschilling]

I do mostly city driving in my 92 4.0 it rarely sees highway. When it finally does on wheeling trips going up into the mountains it rattles/knocks pretty loud depending how far I'm into the pedal. Though every time it seems at a certain point in the drive up the rattles stop (about thirty or forty minutes maybe. I don't have to get into it hard much since is a manual. On the way home I am able get as hard into it as I want with no rattle. I think its timing rattle and i back off if it gets bothersome. But I can literally floor it up and done the mountain highway with just the intake and exhaust screaming. I think the 4.0 needs a good stretch every once in a while. If you have an auto trans you should check it before trying to run the hell outta the engine. Try and give it a good, hard run when you can.

 

[gmanpaint]

I had this issue in a 94. Turned out to be the fuel pump relay was weak. The heat, and the old wiring to it had deteriorated, and caused it not to get the proper voltage, causing it not to send the needed voltage to the fuel pump under load, causing the Ping from low fuel pressure. In my case, it was a simple fix, but not an easy one to diagnose.

I replaced the relay with a lifetime warranty relay from AutoZone. Ping went away instantly. The wires under the relay in the PDB should be checked for age, or if any leads are loose. A Telltale sign of heat, is if the bottoms of a relay are white, they turn yellowish.

I agree with the MAF cleaning, and the plug change as well. MAF sensor should be cleaned frequently anyways, so no harm in doing that. Try swapping in a new relay, and see if that helps you any.

 

[Explorin'VA]

My belt tensioner was bad and caused a noisy rattle during idle and when under load. I replaced it with a cheap one. Fixed the rattle for a while but now the rattle is back. I need to replace it with a ford one when I get a chance. It's worth checking out. Just have someone put the truck in gear and hold the brakes while you crawl under the front and listen to see if the pully is the source of the noise.