I have a 98 Mustang GT with 92,300 miles and have used synthetic since i bought the car with 79,000 miles. The car is fully tuned up. I did an oil change 2 weeks ago and the car has almost 200 miles on the new oil. I use Mobil 1 EP 5W30 with a Mobil 1 oil filter. When starting the car there is a knocking sound comming from the bottom of the engine, by the oil pan. Once it warms up it goes away. I'm not blowing any smoke. Do i need to switch to a thicker synthetic cause i heard mobil 1 is thin?
Engine knocking when cold?
- Thread starter sanitarium16
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Why would such a quality synthetic cause engine knocking?
Patman
Staff member
Sanitarium, what makes you think that the synthetic caused the knocking?
this is a problem on 4.6 motors when using a filter with no or a bad anti drainback valve. i use a Motorcraft or Purolator filter on my 98 GT since they are the same part and have the ADB valve. the only time i ever hear it is when i do an oil change and start it for the first time. i also use Mobil 1 5w30, but i dont use the EP version.
I've heard a few people here say they also have experienced knocking when using Mobil. In fact the day I changed my oil back in early october to Mobil 5w30 EP I experienced knocking for the first few seconds after starting the vehicle. But it only happened once and it was right after changing to the new oil.
The anti-drain back valve doesn't have anything to with it. To better understand how the ADBV works is to look at a dis-assembled filter. It keeps the dirty oil contained in the filter when the engine is shut off or else it would drain back into the pan. And is only useful if the filter is mounted on an angle.
the filters on 4.6L motors are at an angle.
Mobil 1 is a quality filter, i doubt this filter is causing the knocking. Like stated above it only happens when first starting the car, once it warms up its OK. I don't like the sound of it though, and if i need to change out the oil to another brand i will but it must be synthetic. What problems can this cause to the engine?
Try a different oil filter. Mobil 1 may be a good filter but on some engines during cold starts filters can slow the amount of oil to the engine and can cause a knock to be heard. Also if the filter empties then it will take a second or so longer for the oil to reach all the bearings. Easy to find out by using another filter.
Thats what I would do. Its not the oil..
When the engine is shut down, all the oil drains back down to the pan and if it takes to long to get back up to the engine, then something might be hindering it, like the oil filter. I have seen it many times before where a simple change in brands of filter will eliminate this problem.
Thats what I would do. Its not the oil..
When the engine is shut down, all the oil drains back down to the pan and if it takes to long to get back up to the engine, then something might be hindering it, like the oil filter. I have seen it many times before where a simple change in brands of filter will eliminate this problem.
Those engines, along with the 5.4 are VERY picky about filters. I would make DANG sure that the filter you are using has the exact spec's for that engine. Or better yet, go get a Motorcraft FL1A and swap it out to see if that doesn't change it. My 5.4 with the motorcraft filter doesn't knock at all, and that was with starting it up at 6 degrees last week and with M1 10w30.
Schmoe, I hope you didn't mean using a FL1A in a modular engine. These engines use the FL820S oil filter. Totally different threads are used between both filters. The FL820S has metric threads and the FL1A has SAE/Imperial threads.
Whimsey
Whimsey
Piston slap maybe from cold weather? May just sound like it's coming from the bottom. It should only take a couple seconds to stop knocking from a cold start to build up oil pressure, Not until it warms up, That might be a problem. Does anyone know if these engines are prone to piston slap?
piston slap is very rare in these motors.
i think i have an exhaust leak. My exhaust is very tinny sounding. I have a mac off road h-pipe with flowmaster super 40 welded on.
my 98 vic 4.6 makes that knocking noise too sometimes..the last 3 days it was 10 and no knocking noise..then the other day it did one or 3 knocks for a sec. it was 20 out..
We had a similar noise problem 2x in our 5.4L. Once was with a Napa filter... chenging back to Motorcraft removed the noise. The other time was when I used an aftermarket PCV valve. I switched back to a MC PCV valve and the startup noise went away.
You seem to have isolated where the sound is coming from. It might be the oil filter.
You seem to have isolated where the sound is coming from. It might be the oil filter.
i went to fleetguard..
if i change the filter wont oil spill everywhere
I vote for the oil filter. Its easy enough to swap out for a "test". Grab a motorcraft filter.
If the problem doesn't go away, use a different oil at your next oil change.
Try not to change more then one variable at a time.
I assume that Ford allows 5w20 in that engine, than 5w30 probably isn't too thin.
If the problem doesn't go away, use a different oil at your next oil change.
Try not to change more then one variable at a time.
I assume that Ford allows 5w20 in that engine, than 5w30 probably isn't too thin.
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