Hello...Just joined the site...Ive learned many things your site..thanks..I have a '93 f150 4.9 straight 6cyl F.I.

Was selling truck and hadnt started it in around a year..ran fine when last started...but wouldnt start now without spraying gas into the throttlebody...found out it was the front fuel pump..fixed it and started right up...went out 2 days later..wouldnt start again!

called back mobile mechanics and they found a ground wire in-between the 2 tanks that had been rubbing the frame...said it could have been the cause of the 1st pump to go out...well before they came out, the guy who was going to buy it and I were trying to get it started...I sprayed a little bit of starting fluid...it would run, but like crap..nothing like it sounded when we drove it after the fuel pump fix...it just didnt sound right from the 1st turn of the key...Ive started this truck every day for over 7 years..you just know something sounded wrong...I thought the starter was acting up again..these 300's eat starters..kept trying to start it with gas after initial spray of the "death fluid"...still just a hit here and there..motor jumping around all over the place...I quit and went inside...idiot buyer must have sprayed half the can while I was inside for a minute..I came out the front door to smell ether from around the side of the house...I think he put the nail in the coffin...couldnt get it to hit a lick after that...

1st they said it was timing gears??? but we got fire to the plugs and the rotor turned...then maybe head gasket they said??? was going to pull head, upon tearing down, took off valve cover to find 4 bent pushrods out on the side of the rocker arms..They are on the right if looking from the drivers side..I guess intake side?..now there thinking timing gears again??? SO CONFUSED!!!!!

how can I easily check whats wrong?? rotor pointing to #1 cly...#1 piston at TDC... timing mark at 10*...if part of the timing gears was off, would all rockers rock?? or if cam was broke, wouldnt some just sit there?? could all the starting fluid cause such pressure that the valves stayed closed and bent the rods as the cam came around?? hope Im making some sense here?? Any help would be greatly appreciated...ps..sorry for the book thanks for sticking it out till the end.

 

I looked at it further tonight after the post...got under the truck and found the little timing notch on the balancer..etched a line across the balancer so I wouldnt miss it as it went around..wiped off the sawtooth and found the larger notch for 10degrees(easily read once the oil gunk was gone)...lined them up multiple times and everytime, the #1 piston was halfway down, #2 piston was@TDC, rotor pointing to #2 cyl. I went around and around slowly many, many times..this one is beyond me...it looked like all the rockers are going up and down except the ones with the pushrods dislodged...tons of spark jumping off of the coil...any ideas???

 

Sounds like all that ether vaporlocked the engine......might try replacing all the pushrods and go from there....

 

ok...went out tonight and found the correct timing mark...it was the "chiseled" looking mark...cleaned it all up and put a white mark with a grease pencil..easy to see now...went around numerous times...had the timing marks lined up, #1 piston @TDC and the freakin rotor was pointed towards the drivers side headlight/ac compressor area...went around many times again and in the other stroke it would be pointed at the middle of the firewall...180* of where it was landing @TDC and 10* timing...
so it seems the dist. is fine?? could it have broke a tooth? or does this sound more like the timing gears have jumped a tooth or broke a tooth?? Ive read it would be hard to jump as there is no chain...gear on gear...
I did this many times to have the rotor end up in the same 2 places every other time....any help would be greatly appreciated...thanks in advance!

 

Sounds like the cam gear stripped a few teeth. Its kinda a common problem on the 300 engine with the nylon cam gear. Replace the timeing gear set, bent push rods and hope no valves/pistons hit eachother. I can't rember if the 300 I6 is a interferance engine when cam timing jumps.

Too much starting juice most likely caused a prefire and ran the engine backwards jumping cam timing and hopefully with no bent valves or holed pistons.

 

thanks a bunch..I was kinda heading in that direction...how can I diagnose the valves if bent?? compression test? thanks again

 

The 4.9 is NOT an interference engine. Just an FYI.

 

non interference is good, right? what caused the 4 pushrods to come out? piston hitting valve?

 

I am new here and not a 300 I-6 expert (yet - I just bought one) but I do a lot of work on italian cars with interference engines. Anyway, an "interference engine" is one where if timing is off enough the pistons will slam into the valves while they are open. Big problem if this happens - total engine rebuild. So, since the 300 is a non-interference engine according to the post above, the pushrods being bent/coming out was caused by something else. It could be related to the timing being off but not because of piston/valve contact.

 

well this is going to be a good one, so be prepared...
disassembled the motor today...We started by doing a complete cpmpression test all the way across the cyls...results: #1=110, #2=110, #3=5, #4=0, #5=0, #6=120 whats up with that??
so now were thinking, blown head gasket?? broken valves??? hole in piston??? broken rings?? hole in sleeve?? NONE Of THE ABOVE everything looked great, except the #1 piston had a little gouge on it..small than the eraser on a pencil...looked like some little small chunk of metal went thru and got hit by piston..you could see a tiny spot of the #1 combustion chamber on the head...no broken rings floating around...the pistons looked great except for the little gouge...the cylinder walls looked good...
went to check head...all looked pretty good...the head gasket didnt look blown anywhere to where there would be no compression...but all the pushrods were slightly bent...some worse than others..mainly the ones on #1,#3,#4,#5...so what caused all the rods to bend??
timing still seemed the culprit....so we figured for sure it was the cam gear with a sheared off tooth or teeth, being the rotor still pointed to the front drivers headlight @TDC with 10 degrees timing,instead of pointing to the #1 cyl...Ive turned this motor over so many times with the same results...had the spark plugs out..turned motor by hand...the rotor ended up pointing directly at the driver headlight/ac comprssor area...so the timing had to be way off...
so we decided to pull the timing cover off...what else could it be?? if it was the dist. the rotor wouldnt go around...so we pulled the timing cover off and looked for damage...the gears were in awesome shape...not even a chipped tooth or mark of any kindwhat the freak???how could this be?? what else could make it so far out of time...we lined up the 2 dots on the gears...(dots close to each other) as I have read on this and other forums...piston came to TDC as we had the head off and could see it clearly.....rotor still kept pointing to the driver headlight???
so we started to pull the distibutor...it didnt want to come out...like it was in a bind??...finally after some major muscle and rocking back and forth it popped out...shouldnt it just pull out easily?? We looked at the gears on it..they seemed good...shear pin intact...maybe a couple marks on the gears, but no missing teeth...rears on camshaft looked good..no missing teeth, etc...put it back in where we thought it should be(pointing to #1 cyl) went in easy...came right back out again without any effort...turned motor over with solinoid on fender...engine sounded free and smooth..no knocks or weird sounds of any kind...pistons and crank and gears all worked flawless and the rotor button lined up with #1 cyl everytime...
also, I forgot to mention while doing comp test, we had the #3 cyl plug out and turned over motor and a mix of gas and oil squirted out on every compression stroke...#4 was dry...could this have been all the ether and gas the idiot buyer squirted into it and previously mentioned?? all the gas and starting fluid was squirted into the right side of the throttle body...didnt know if that would cause the gas to go to #1,#2,#3 cylinders?? and what would all thet fluid do??? too much pressure that had to go somewhere...Please help if you can..this one is beyond about 4 of us...2 good mechanics and 2 shadetree mechanics...any ideas??? could the distributor jumped a tooth or 2??? thats the only thing we can think of...why else or HOW ELSE could it get so far out of time??? Unless someone broke into my truck and loosened the dist and took it out an put it back in a tooth or so off...that could maybe cause some of the damage???...
having head checked tomorrow for bent valves...warped or cracked head, etc...

 

well this is going to be a good one, so be prepared...
disassembled the motor today...We started by doing a complete cpmpression test all the way across the cyls...results: #1=110, #2=110, #3=5, #4=0, #5=0, #6=120 whats up with that??
so now were thinking, blown head gasket?? broken valves??? hole in piston??? broken rings?? hole in sleeve?? NONE Of THE ABOVE everything looked great, except the #1 piston had a little gouge on it..small than the eraser on a pencil...looked like some little small chunk of metal went thru and got hit by piston..you could see a tiny spot of the #1 combustion chamber on the head...no broken rings floating around...the pistons looked great except for the little gouge...the cylinder walls looked good...
went to check head...all looked pretty good...the head gasket didnt look blown anywhere to where there would be no compression...but all the pushrods were slightly bent...some worse than others..mainly the ones on #1,#3,#4,#5...so what caused all the rods to bend??
timing still seemed the culprit....so we figured for sure it was the cam gear with a sheared off tooth or teeth, being the rotor still pointed to the front drivers headlight @TDC with 10 degrees timing,instead of pointing to the #1 cyl...Ive turned this motor over so many times with the same results...had the spark plugs out..turned motor by hand...the rotor ended up pointing directly at the driver headlight/ac comprssor area...so the timing had to be way off...
so we decided to pull the timing cover off...what else could it be?? if it was the dist. the rotor wouldnt go around...so we pulled the timing cover off and looked for damage...the gears were in awesome shape...not even a chipped tooth or mark of any kindwhat the freak???how could this be?? what else could make it so far out of time...we lined up the 2 dots on the gears...(dots close to each other) as I have read on this and other forums...piston came to TDC as we had the head off and could see it clearly.....rotor still kept pointing to the driver headlight???
so we started to pull the distibutor...it didnt want to come out...like it was in a bind??...finally after some major muscle and rocking back and forth it popped out...shouldnt it just pull out easily?? We looked at the gears on it..they seemed good...shear pin intact...maybe a couple marks on the gears, but no missing teeth...rears on camshaft looked good..no missing teeth, etc...put it back in where we thought it should be(pointing to #1 cyl) went in easy...came right back out again without any effort...turned motor over with solinoid on fender...engine sounded free and smooth..no knocks or weird sounds of any kind...pistons and crank and gears all worked flawless and the rotor button lined up with #1 cyl everytime...
also, I forgot to mention while doing comp test, we had the #3 cyl plug out and turned over motor and a mix of gas and oil squirted out on every compression stroke...#4 was dry...could this have been all the ether and gas the idiot buyer squirted into it and previously mentioned?? all the gas and starting fluid was squirted into the right side of the throttle body...didnt know if that would cause the gas to go to #1,#2,#3 cylinders?? and what would all thet fluid do??? too much pressure that had to go somewhere...Please help if you can..this one is beyond about 4 of us...2 good mechanics and 2 shadetree mechanics...any ideas??? could the distributor jumped a tooth or 2??? thats the only thing we can think of...why else or HOW ELSE could it get so far out of time??? Unless someone broke into my truck and loosened the dist and took it out an put it back in a tooth or so off...that could maybe cause some of the damage???...
having head checked tomorrow for bent valves...warped or cracked head, etc...

 

dist gear was fine....shear pin fine...timing gears look great...machine shop said the head gasket was blown between #3, #4 & #5...#3 valve guide cracked...all valves checked out good...no cracks in head...

the thing had to jump time at the dist gear...there is no other explaination?? Unless a gremlin pulled out the dist. in the middle of the night and put it back in a tooth or 2 out??? Ive had other people say its possible, but very, very rare....and the dist was a bear to get out...like it was stuck or in a bind..the guy trying to pull on it weighed over 300 lbs...big guy...I'm 6'4" 230 lbs and I couldnt get it to budge...

putting it back together tomorrow with a set of new pushrods...thanks for all your help, unless you can think of any other cause?
<!-- / message -->

 

As mentioned, the 300 six is a non interference motor. No matter what position the cam
or crankshaft is in, the pistons can never hit the valves.

So the question is what caused the bent push rods.

If it was caused by a liquid that filled the cylinders, was it gasoline due to leaking
injectors or water/antifreeze from the blown head gasket?

When you pulled the head was there any liquid in any of the cylinders?

Have you drained the engine oil to verify if there is any gasoline or antifreeze?

After you removed the cylinder head and cranked the engine so cylinder one was at
TDC on the compression stroke, did the timing mark on the damper line up with the
zero mark on the timing cover?

If it didn't, the rubber that joins the outer and inner part of the damper together may be
defective allowing the timing mark to change. The V notch in the damper is not the
timing mark. The timing mark is a faint line scribe mark that is about 6.5 inches in a
counter clockwise direction from the V notch.

 

The distrubtor hard comeing out is kinda normal. The oil will coke up on the lower end and that locks in in place when you try to pull it out. In junkyards I have broken off dizzy's before trying to get them out! Use some PB blaster or Equ to loosen up that crud.

The only other thing that causes bent push rods, is the engine was over reved.

 

there was liquid in the #3 piston...a bunch gushed out right before check the compression..we had a few plugs out trying to look into the plug holes...

The timing mark I used was the correct one...tiny little line..not the square notch(which looks like a file on edge did it)...the v-notch Im referring to in on the sawtooth/degree thing(not sure what its called) it has many little v's and one big one at 10 degrees...you can easily read all the increments...we took off the timing cover and the gears were fine and both timing dots lined right up when @TDC....its the dist/rotor that was pointing in the wrong direction...

if the damper/balancer has slipped the #1 piston wouldnt hit TDC when the marks lined up..correct? believe me..there have been close to six guys working on this thing in the last week...4 of them are pretty knowledgable and 3 are mechanics by profession...no one can figure it out???

like I said before..one valve guide cracked on the #3 cyl...gas in the oil...antifreeze in the oil...machine shop says head is good..valves were seated nicely...no bent valves..just all pushrods bent.."ALL" of them..#1,#3,#4,#5 intake side pushrods push out and stting against the side of their rockers...had a blown head gasket due to the fluid(gas & or water) or starting fluid or both or major combustion due to all the gas & starting fluid sitting in the cylinders...timing gears are fine..cam gear is the metal gear, so it couldnt have spun or slipped...the only weak link is the distributor...all rocker arms go up and down as they should(no broke cam)...rotor turns around fine, always ending up in the same place if the timing is set at 10*TDC or if the timing gear dots are lined up @TDC..I have never seen anything like this before..its beyond all of us...