Can't Get Rid of Engine Ping/Knock

[luvmonterey]

Hi all. Hope someone can help me. I have a '94 XLT with 225k miles. Engine has been knocking terribly and I haven't been able to get it to stop. I have done the following:

Replaced plugs, wires, coil pack.
Run Seafoam through the intake twice, let it sit, and then ran the engine about 15 miles at 3k rpm. Check engine light went on when I did this last, but then went off. I ran the engine pretty hard. Then changed the oil.

I'm running 91 octane premium because anything less knocks worse. I have been running Arco gas recently. It's the least expensive around generally, and am wondering if that may be part of the problem?

Also wondering if a blown head gasket could cause knock. I am loosing some coolant, but I think it could be a slow leak from around the neck of the thermostat cover, as there is some buildup around the hose there. I can also smell coolant under the hood. How can I diagnose or rule out a bad head gasket? Any help would be appreciated! Thanks!

 

[2stroke]

This sounds like it could be a bad lower intake manifold gasket. Both air intake, and coolant ports go through the intake manifold, and a vacuum leak is a common cause of pinging.

 

[luvmonterey]

This sounds like it could be a bad lower intake manifold gasket. Both air intake, and coolant ports go through the intake manifold, and a vacuum leak is a common cause of pinging.

Well that would be easier to deal with than a head gasket I would imagine. Is there any way to diagnose, short of just doing the tear down and replacement?

 

[Rick]

I have to clean my MAF regularly in my '93 or my engine knocks. Here is a thread on cleaning the MAF on a 2nd gen. http://www.explorerforum.com/forums...af-sensor-and-the-iac-valve-2002-2003.339793/ The procedure is the same, but the 1st gen MAF only has one wire to clean.

In the thread he shows MAF cleaner, you can also use electronic contact cleaner with the same results, just don't use brake cleaner, or anything, but cleaners made for electronics.

 

[Rhett]

I thought the worst (lim gasket leak) but on my truck, I had cracks in my intake tube (the tube from the air filter to the throttle body) and once I repaired the tube, pinging disappeared. And I can tell you -- I had pretty bad, persistent partial throttle /full throttle pinging, even on 93 octane gas. Unmetered air is really bad on our trucks it seems.

You can also check for vac leaks on the vac lines, and on the vac octopus on the upper intake manifold. Not all of those ports are used, and they are supposed to have a cap on them. Every now and then a cap blows off, or wears out and falls off.

 

[luvmonterey]

I have to clean my MAF regularly in my '93 or my engine knocks. Here is a thread on cleaning the MAF on a 2nd gen. http://www.explorerforum.com/forums...af-sensor-and-the-iac-valve-2002-2003.339793/ The procedure is the same, but the 1st gen MAF only has one wire to clean.

In the thread he shows MAF cleaner, you can also use electronic contact cleaner with the same results, just don't use brake cleaner, or anything, but cleaners made for electronics.

I completely forgot about the MAF. It has been a while since I cleaned it, so I picked up a can of contact cleaner when I was out and cleaned the MAF in the parking lot. I drove about 18 miles back home and it seems to be better, but it could just be my imagination also. I have about a quarter tank left, and will also try some better gas this time around. Thanks for the suggestion regarding the MAF!

 

[luvmonterey]

I thought the worst (lim gasket leak) but on my truck, I had cracks in my intake tube (the tube from the air filter to the throttle body) and once I repaired the tube, pinging disappeared. And I can tell you -- I had pretty bad, persistent partial throttle /full throttle pinging, even on 93 octane gas. Unmetered air is really bad on our trucks it seems.

You can also check for vac leaks on the vac lines, and on the vac octopus on the upper intake manifold. Not all of those ports are used, and they are supposed to have a cap on them. Every now and then a cap blows off, or wears out and falls off.

Thanks for the suggestions. I will check for leaks on the intake tube. I know that the rubber seal at the end that connects to the throttle body on my '94 is falling apart. I have been meaning to go to a yard to see if I can find a replacement, as I'm sure Ford no longer makes them. My vacuume hoses seem to be ok. On the octopus, if I do remove a cap, the engine immediately runs really rough, and I have had hoses blow off before. This seems to be a different issue. The pinging seems to be worse between 1500-2000 rpm in the higher gears, at highway speeds or near them on flat roads.

 

[Rhett]

Thanks for the suggestions. I will check for leaks on the intake tube. I know that the rubber seal at the end that connects to the throttle body on my '94 is falling apart. I have been meaning to go to a yard to see if I can find a replacement, as I'm sure Ford no longer makes them.

I repaired mine using Permatex Black. It dries to a rubber-like material and it sealed my tube (the end was getting ragged just like yours). Pinging was as you described -- worse on partial throttle, and actually at full throttle or near-WOT it was ok, no pinging then. I figure the unmetered air was really leaning the air/fuel mix.

The other option is either junkyard or e-bay...I used to see intake tubes on e-bay but they were like $180, so I said, "I'll try the Permatex Black first...". If my pipe had been cracked everywhere, then yes, I would have bought a replacement. I may still...

 

[luvmonterey]

I repaired mine using Permatex Black. It dries to a rubber-like material and it sealed my tube (the end was getting ragged just like yours). Pinging was as you described -- worse on partial throttle, and actually at full throttle or near-WOT it was ok, no pinging then. I figure the unmetered air was really leaning the air/fuel mix.

The other option is either junkyard or e-bay...I used to see intake tubes on e-bay but they were like $180, so I said, "I'll try the Permatex Black first...". If my pipe had been cracked everywhere, then yes, I would have bought a replacement. I may still...

I will check out my intake tube more carefully for cracks. Was yours cracked in the flexible ribbed areas or in other spots? I was just thinking about trying to repair the rubber seal on the end with black Gorilla duct tape. It's just the bottom portion that is really worn out. Thanks for the suggestions!

 

[Rhett]

I will check out my intake tube more carefully for cracks. Was yours cracked in the flexible ribbed areas or in other spots? I was just thinking about trying to repair the rubber seal on the end with black Gorilla duct tape. It's just the bottom portion that is really worn out. Thanks for the suggestions!

It was mainly the end by the throttle body that was chewed up. Permatex Black is messy. I didn't want to use tape because I thought tape might wear out from heat cycles. If Gorilla tape is anything like Gorilla glue then maybe it is good stuff and will hold for a long time.

 

[luvmonterey]

It was mainly the end by the throttle body that was chewed up. Permatex Black is messy. I didn't want to use tape because I thought tape might wear out from heat cycles. If Gorilla tape is anything like Gorilla glue then maybe it is good stuff and will hold for a long time.

I will try it and let you know how it goes. It's very strong and sticky tape. Much thicker and heavier duty than traditional duct tape. It really sticks, plus it's black.

 

[RangerX]

Well this is very interesting. I've have pinging/ marbling for a while now, and have recently noticed my intake tube has not just cracks but actual holes. Never made the connection until now! Thanks.

 

[RangerX]

I was thinking of using this to patch, any thoughts on it?
https://www.amazon.com/FiberFix-Rep...coding=UTF8&psc=1&refRID=STK7V0QK6TEQT2KJY5VM

 

[shucker1]

What about that "Flex Seal" stuff they sell on TV late night infomercials?

If he can cut a boat in half then fix it and ride around like noting happened..

Who knows.

Just kidding.

There has got to be a way to fab up a new inlet hose.

 

[luvmonterey]

I was thinking of using this to patch, any thoughts on it?
https://www.amazon.com/FiberFix-Rep...coding=UTF8&psc=1&refRID=STK7V0QK6TEQT2KJY5VM

I think the issue with any fix is that it is going to be exposed to high and prolonged heat, over and over. Likely any of these fixes is going to be somewhat temporary, but I will take temporary over the pinging. I really want it to stop.

 

[Rick]

Maybe silicone tape would work well since it can handle high heat.
https://www.amazon.com/XFasten-Sili...981&sr=1-2-spons&keywords=silicone+tape&psc=1

 

[Highflow50]

At 225k I would look at the timing chain. It could be stretched out a bit.

 

[natenkiki2004]

Just throwing this out there... I've never gotten rid of my ping, just tamed it. Upper and lower intake gaskets, throttle body gasket, intake tube swap (and inspection), valve cover gaskets, timing gasket, timing set, new silicone vacuum hoses with minimal loops... Nothing's fixed it. I run premium gas and it doesn't ping 98% of the time. If I put regular in, it will ping on cold nights at highway speed on flat ground. I think some of us just have to deal with it, whether it's inherent to older computers, caused by carbon build up or a worn engine.

 

[luvmonterey]

Maybe silicone tape would work well since it can handle high heat.
https://www.amazon.com/XFasten-Sili...981&sr=1-2-spons&keywords=silicone+tape&psc=1

It looks like it would probably work as well as anything else available. Too bad it's not 1.5" or 2", but maybe those widths are available. I think the biggest issue with using any tape product is going to be how well the adhesive withstands heat. At least with the silicone tape, it's not going to melt, which is a definite advantage.

 

[luvmonterey]

At 225k I would look at the timing chain. It could be stretched out a bit.

Yes, I have thought about that also. Not something I am looking forward to replacing. I am hoping that since the pinging is somewhat intermittent, in that it gets really bad, subsides some, goes away, comes back, that it's not the chain, which I would think, if was a cause, would cause the issue to be more consistent. I could be wrong though. Most people on this site know more than I do. That's why I'm here!