Well, I started another thread on here asking about putting a new PCV valve in, which I finally did. I've had a slight knocking when I first start up my truck that eventually seems to go away once it's at normal operating temperature. I was hoping changing the PCV valve might help but unfortunately it's still knocking when I first start it up. What do you guys suggest I try to get rid of the knocking? I use 5W30 oil which is recommended. That's what I've always used. Should I try going a little heavier starting weight like 10w30 since the problem only seems to be when the engine is cold? Should I try sea foam and see if that helps? Maybe I have some carbon buildup in there, I don't know. I just changed my oil about a month ago so I guess I'd have to wait a while before going the sea foam route. Anyway, any suggestions would be appreciated. Thanks.

 

Where is the knock coming from & what does it sound like????

Is it mechanical, from the bottom, or top end, or from the combustion chamber area, or is it spark knock????

If you think it's CCDI, then you can treat it now, by adding a 20oz container of Chevron Concentrate Plus at the pump, then filling up with Chevron, Texaco, or Caltex gas, which already have Techron in them, so this will raise the treat rate 10X above the pump gas level & will usually tidy things up in one treatment, without contaminating the sump oil.

Run most of the treated tank out with some spirited driving & daily rpm's at or above 3500 for two or three miles, to loosen & get rid of combstion chamber carbon deposis. It'll also tidy up the intake valves & fuel injectors.

Other sources of start up knock could be a faulty oil filter anti drain back valve, or filter of poor design, or maybe the lifters bleeding down.

Give us some more clues as to what the knock sounds like & where it's coming from & maybe we can make a better guess.

Some knock thoughts for pondering.

 

All I can tell you is that I think it sounds like it's coming from the bottom. I'm starting to think it might be the oil filter because I think it's been doing it since I changed it a month ago. You're not the first person to suggest faulty oil filter anti drain back valve. I hate to have to do another change so soon after the last one, but I'll give it a try. If I still have the issue then I'll try your suggestion and see what happens. Should I stick with the 5w30 or bump it up to 10w30? Also, I've been using high mileage oil for the past 2 years. Someone mentioned to me recently that high mileage oil can cause problems with the seals. Can I go right back to regular oil after using high mileage for 2 years or would it be better to stick with the high mileage? Thanks for your help.

 

You can change the oil filter without having to do a complete oil change. Remove your present filter, install a new Motorcraft filter, add a quart of oil and you should be good to go. The sooner you get rid of the knock the better.

 

You know I feel really stupid for asking this but you can actually remove an oil filter without having to drain all of the oil out first? I honestly didn't know you could do that. I guess it makes sense since the oil isn't getting pumped around the engine. I've never removed a filter without removing all of the oil first so I just always assumed you had to. Anyway, thanks for the info.

 

I agree with michigan66, put a new Motorcraft oil filter on it & no you don't have to drain the oil sump to change the oil filter.

5W-30 is fine for your engine, as that weight was orgionally specified for it, but now Ford has back specified 5W-20 as being ok for the Vulcan 3.0L engine.

If the engine oil filter is mounted inverted, you can completely prefill it with oil, then screw it on & be good to go.

If it's mounted sideways, such that you can't prefill it, screw it on, then disable the fuel pump by thumping & tripping or disconnecting the inertia switch, so the engine wont start, then crank the engine until the low oil pressure warning light goes out (but don't crank longer than 15 seconds at a time, so you don't overheat the starter motor).

This will prime the oil pump, fill the new oil filter, burp the air out & build some system oil pressure, so you don't get a dry start.
Check your oil level afterward if you do this.

If you prime the system each time you change the vehicles oil & filter, over time it'll thank you for not starting it up dry, after each of those oil & filter changes.

If replacing the oil filter doesn't fix the knock, with the noise being low down in the engine, it could be "Pistion Slap".

Over the years Ford has bored, stroked & trimmed the piston skirts off, to the extent that if the factory isn't mindful of piston diameter tolerances & installs some under sized ones, we can get piston slap on a cold start, as the piston wobbles in it's bore at the bottom of it's stroke, just as it changes direction.

As the engine warms up & things expand, sometimes it'll tighten up & stop knocking, sometimes not, if things are too loose.

Combustion Chamber Deposit Interference (CCDI) caused by the piston making contact with the head in the "squish zone" through carbon deposits on both the piston crown & head, can make a sound on a cold start called "marble noise", it sorta sounds like marbles clacking together in a sack, & will slowly diminish as the engine warms & things expand to give clearance in the "squish zone".
This noise is sorta a metallic clacking & is loudest mdway on the block, where the head & block meet.
The Techron decarb treatment & use of gas with it, can help this condition.

More engine knock thoughts for consideration.

 

I agree with michigan66, put a new Motorcraft oil filter on it & no you don't have to drain the oil sump to change the oil filter.

5W-30 is fine for your engine, as that weight was orgionally specified for it, but now Ford has back specified 5W-20 as being ok for the Vulcan 3.0L engine.

If the engine oil filter is mounted inverted, you can completely prefill it with oil, then screw it on & be good to go.

If it's mounted sideways, such that you can't prefill it, screw it on, then disable the fuel pump by thumping & tripping or disconnecting the inertia switch, so the engine wont start, then crank the engine until the low oil pressure warning light goes out (but don't crank longer than 15 seconds at a time, so you don't overheat the starter motor).

This will prime the oil pump, fill the new oil filter, burp the air out & build some system oil pressure, so you don't get a dry start.
Check your oil level afterward if you do this.

If you prime the system each time you change the vehicles oil & filter, over time it'll thank you for not starting it up dry, after each of those oil & filter changes.

If replacing the oil filter doesn't fix the knock, with the noise being low down in the engine, it could be "Pistion Slap".

Over the years Ford has bored, stroked & trimmed the piston skirts off, to the extent that if the factory isn't mindful of piston diameter tolerances & installs some under sized ones, we can get piston slap on a cold start, as the piston wobbles in it's bore at the bottom of it's stroke, just as it changes direction.

As the engine warms up & things expand, sometimes it'll tighten up & stop knocking, sometimes not, if things are too loose.

Combustion Chamber Deposit Interference (CCDI) caused by the piston making contact with the head in the "squish zone" through carbon deposits on both the piston crown & head, can make a sound on a cold start called "marble noise", it sorta sounds like marbles clacking together in a sack, & will slowly diminish as the engine warms & things expand to give clearance in the "squish zone".
This noise is sorta a metallic clacking & is loudest mdway on the block, where the head & block meet.
The Techron decarb treatment & use of gas with it, can help this condition.

More engine knock thoughts for consideration.

 

That's great advice pawpaw, thanks! People always talk about filling the oil filter before putting it in but I have one of those that goes in sideways so it's hard to do. I'll do what you said about disconnecting the inertia switch. That's what I do when replacing the fuel filter so I'll just do the same thing for the oil filter from now on. I don't think I have a low pressure oil light though, just one of those dummy gauges. At least I've never noticed it pop on before when pulling the switch when changing my fuel filter. If I don't have a light come on, how long do you suggest I keep cranking the engine for? Thanks for the advice.

 

Crank it at least until you have oil pressure on the gauge, or not more than 15 seconds at a time, so as not to overheat the starter motor.

I usually crank mine about 10 seconds.

EDIT: BTW, if you decide to use the Techron in the gas tank to decarb the engine, you don't have to change the crankcase lube, unless your persnickety about things.

When I use the Techron, I usually wait to do so right before an oil change, so any carbon it removes, that might find it's way into the lube, comes out with the old oil, but if you don't think your engine is loaded up, I would't worry about it, as the oil filter can grab it.

 

Well, just to update you guys, I threw a new filter on a bit earlier and I'm still hearing that slight knock at start up and it still goes away when warmed up. I'm going to give your suggestion a try pawpaw and see what happens. Maybe I'm making a mountain out of a molehill here because it's not like it's a loud knock. You can hear it just a little bit until it's warmed up then you can't hear it at all. I still don't like the fact that it's there though so on to the next step I guess. Thanks.

 

It could also be connecting rod bearings. The older 300 cid in-line 6's were well known for rod bearings knocking on a cold start, especially after the 100,000 mile mark. Rod bearings usually knock for only about 2 or 3 seconds, or, while the oil pressure builds up. I'm told that it is only possible to change rod bearings with the engine in the vehicle if the transmission is out. The oil pan has to come off it will only clear if the transmission, bell housing and fly wheel are out of the way.

 

With the knock coming about after the last oil change & suspecting the oil filter was a logical thought.

Did you replace it with the specified Motorcraft filter????

Well the Techron decarb will likely tidy up the intake valves, combustion chamber & fuel injectors, so even if CCDI isn't your problem, everything will get a thorough cleaning & thats a good thing.

AutoZone had a 2 for one deal on the 12oz size of Techron, thats less cost than a 20oz size.

Will be interesting to hear how it goes, so keep us posted.

 

Yeah, I've always used the same recommended filter from Motorcraft. FL-400s. I have that memorized since I've changed my oil so many times! lol Anyway, I have a 19.5 gallon tank in this truck. Which size of the Techron treatment would you recommend to try for that size gas tank? I'm assuming this is one of those treatments that you have to wait until the tank is almost empty to put it in right? If that's the case then it'll be a few days before I can do it since I'm still at a half tank. I'll keep you posted, thanks.

 

One more thing pawpaw, is it OK to use that techron treatment with any gas or is it best used with Chevron or Texaco? I ask that because I don't have either gas station anywhere near me so I have to go with someone else. Thanks.

 

Yup it's best to use a gas with the same ad pack chemistry as the additive, so they are synergistic, meaning that the chemistries are not fighting each other, but working together & in such a way that the sum total effect is greater than the sum of the individuals!!!!!
That way we get the most cleaning action for the buck spent!!!!

So for the optimum effect, it's best to use the Techron with a Chevron, Texaco, or Caltex gas that alredy has some Techron in it & if your going to do that, run most of the present tank out before adding the Techron & filling up at the pump.

Techron can be used with any fuel, but we may not get it's full effect if the other fuels ad pack chemistry & Techron aren't synergistic.

So, if we're going to use another fuel, just add the Techron at the pump before tanking up, so we get a good mixing as we fill.

The 20oz size is for up to 20gal, so it's a one/oz per gallon treat rate.

If AutoZone still has their 12oz size at a two for one deal on for Techron, you could get two 12 oz bottles for less cost than the 20oz size & have some left over for the lawn & garden equiptment!!!!

After adding it, do some daily spirited driving, with accelerations & runs above 3500 rpm for 2-3 miles to get rid of any carbon deposits the Techron has loosened up & run most of the treated tank out.

If you suspect the engine is loaded up with carbon, do a second treatment, then continue to use a Techron treated gas & you shouldn't have to use any more Techron Concentrate!!!!

EDIT: We could get the same cleaning effect with the Techron fuels alone, it would just take longer & require about 5 tanks, or 1000 miles of driving.