6.0 long crank time ?

[06F250PSD]

I have a 6.0 that has been taking longer than ever to start for the last few weeks. This morning it was down to 20 deg. F and it took a solid 5 seconds of cranking before it fired up. (I know Ford says up to 5 sec. in cold weather is normal but it never did this last winter) Once it starts it sounds fine and runs smooth. Although twice I heard a loud thump sound from under the hood as it was warming up. I'm trying to figure out what is causing this and after researching on here and talking to different people I am more confused than ever

So heres a little more info. to help anyone that might want to tell me something I have or haven't heard yet.


I just changed the fuel filters and oil a week or so ago. I put 15w40 in and now realize I should have used 10w30 since winter is coming. Could this be the problem? I dont think so because it started having long crank times before the oil change.

Seems to be worse when its cold but doesn't improve much when warm.

I buy good diesel (not bio blend) from a station that I haven't had any problems with in the past. I also use power service additive on a regular basis and drive it hard at times (ok most of the time) to keep the turbo and egr cleaned out.

Thanks in advance!!

[D-Wayne's F350]

Sorry i cant help but i have the same problem so in subscribing....

[dantry]

Im not saying I have had the exact problem that because simply im not a diesel mechanic by no means, however my 06 did the same thing and eventually it would take longer and longer until it eventually would crank and crank but not turn over. The issue ended up being the oil was unable to get to the injectors. Like I said I obviously can say that this is definitely what you have but its something to think about. Good luck hope it pans out for you

[diablos30]

it could be many things, i would start by checking ficm voltage.

[Carl(05/6.0L/BullyDogGT)]

its the 15w40 oil. That engine was made to run on 10w30 during any season. we have 5 6.0s, all acted funny on 15w40. talked to a long time powerstroke mechanic who talked to navistar about it, they said only run 10w30 in them, so we did, all problems went away. take that oil out and put in 10w30.

[06F250PSD]

Ok thought about the oil but it was doing it in warm weather (50s) and that is the oil the manual recommended. It does say 10w 30 for temp below 30 so I think I might try that.

[Carl(05/6.0L/BullyDogGT)]

What did you find out?

[06F250PSD]

I read somewhere (on here I think) that it is possible to get air in the high pressure oil system and that in order to clear it Ford recamendeds doing 12 hard accellerations from 25 to 50. Then letting the truck sit for 5 min. and restarting and see if the crank time shortens. Needless to stay I tried this and it didn't make any difference.

I started thinking maybe I just got some bad fuel. I avoid bio blends because I notice the difference with them and they seem to cause longer cranks. Since I dont drive much (I work 5 min. from home) I am waiting to get all the fuel out and I am going to try refueling somewhere else and see what happens. It is back in the 50s now here and lows at night are only 42. Right now I am down to a half tank of fuel and the truck seems fine. So the power service I added to the tank got mixed around and is helping, I ran out the bad stuff, it is warmer, I dont know...For now I'm not really worried about it. We'll see if the problem returns and if so I will let you guys know.

[bigmic]

I'm also having long start times. Its been in the 5o's here and I'm running 15w40 for a few more weeks then changing to 10w30. I have also had times when I shut off the truck and restart it with in 30 to 40 min and it wont start then after a hour wait it will start but cranks up to 15sec to get going. The ford dealer said it mite be a High pressure oil system fitting that mite cause it.

[06diesel350]

Mine was doing the same thing a little while ago, and my dealer ended up putting in the updated STC fitting and replacing the dummy plugs. The diesel tech at the dealer told me my long crank time was caused by a high pressure oil leak.

The STC fitting and dummy plug replacement fixed the problem right up.

Something else for you to consider...