Get the overhead done? Or no?
 

Well, now that my truck has a whopping 200,000 miles on it, I'm due for my second Cummins recommended overhead. I understand the reasons for it, and have seen what happens when a Cummins never gets overheads, but I am hesitating. The reason I am hesitating is because I am getting the best fuel mileage out of my truck that I have ever gotten. I'm currently averaging 6.19 mpg, and have had some trips average over 7 mpg. It is a virtual guarantee that my mpg will drop after the overhead, and how long it will take to go back up is anyone's guess.

Part of me is saying that I need to get it done, because it is a preventative maintenance item, but another part of me is saying "If it ain't broke, don't fix it". What say you, all the CAD experts?

Just set the truck on fire and collect the insurance. We all know it's only a matter of time anyway. :)

Re: Get the overhead done? Or no?
 

I am a firm believer in PM's and manufacturer's reccos. I had mine done at 210k last month at Cummins NW and have not lost any mpg.

Re: Get the overhead done? Or no?
 

When I had my first one done at 110K, I noticed a definite mpg drop. I honestly don't remember when it started to go back up. All I know is that I started getting 6+ mpg about 30,000 miles ago, and I hate to ruin a good thing. But I know that the overheads are important, especially on Cummins.

I just had my C-15 done. Last one was 113,000 miles ago....they told me yesterday to get it done sooner...suggested 65,000. All but 1 injector were out of wack..and 4 exhaust valves as well.

When I brought mine in the service manager asked why, did your MPG drop? I said no and he said I shouldn't have it done. I wanted it done anyways and everything was perfect except for the jake spring which was broken.

Cummins are much different. If you don't get them done, you can get valve slap against the pistons, causing wear on the crankshaft.

I have an acquaintence in Las Vegas that does insurance adjustments on Commercial equipment. He was telling me the other day about the surge in "Fires Of Mysterious Origin" reports he is handling lately.

He says even the trucks that are salvagable/repairable are going for half of what he could have gotten a year ago.

I told him to find me one so I can start out on the cheap. He has a nice car hauler, but I have never hauled cars before. The trailer was bent up but the tractor is good.

I have one friend who doesn't an overhead every year, regardless of the miles. I would do what the manufacturer suggests. After all, they built it. :wink:

I've already decided to do it. I'm curious if it will affect my mpg this time.

Mine is a detroit, but the mpg dropped on it too. I was told that they may have got the valves a little tight. This makes me wonder if there would be a benefit to requesting that they be set to the maximum recommended "looseness". You would probably need to have the overhead ran more often, but if it effects the mpg that much, it might be worth it.

How long does this loss of MPG last? My second truck is getting bad fuel mileage. I bought it with 316,000 miles on it and had the overhead done right away.

The truck has about 345,000 on it now I think and it's only around 6mpg. About 6.5 deadhead while the other truck is more like 7.7 mpg.

I took it to the dealer and the CAC had a hole in it and also the EGR Valve was replaced but it's back on the road now and not too much better.

merrick4...... hmmmmm........ must be a new member at CAD..... :lol: :lol: :lol:

When I took my truck into KW for its initial overhead, I lost mpg. For the second, I went to Cummins. They said I shouldn't have lost any mileage and that it was probably overtightened the first time. After they performed the job, there was no change. I was back at Cummins not too long ago for some other work and was going to have them run it again. It had been over 100,000 since the last. They asked if it was running worse. I said no but manufacturer's recommendation. Their response was unless I'm noticing that it's running rougher, it's not necessary...but it wasn't going to hurt anything. KW said run it as often as possible :roll: :lol: Well, maybe not, but certainly as often as they could justify.

Run it.

Don't give them an excuse to not honor a warranty claim because you didn't run it as they recomended, they will look for any excuse to void a claim.

What he said :D

Ain't that the truth. :lol:

How much does an overhead cost? (just curious)

Last one ran me about $250 from what I recall.

I was out of warranty by then. During the warranty period, everything goes by the book.

$264.99

What all do they do... adjust the valves and inspect everything?

Pull the heads, adjust the valves, check the jake and all the moving components in the upper end.

Well, the friend of mine, has ISX, at a bit over 400 grand, never run it. I mean overhead... :roll:
One suggestion, if you did experience fuel mileage drop after the last one.
Go to a different people for that service. Should be quiet the opposite, if it was done properly!

I get all my work done at that shop, because I trust them. I may take it to the local Cummins shop, though. Depends how much they charge.

I think it depends on who does the overhead. just because you brought it to a k.w. dealer or any other shop, does not mean much. one day they might have a a person doing the overhead that was trained to do it a specific way & another time at the same place you may get someone else who was trained to do it slightly different.


I had mine done 4 months ago & after driving my truck for 10 years & having the overhead done every 100,000 miles this last time done at freightliner in decatur al, my truck has more power then it did when I first bought the truck. it does blow out a lil more black smoke from the stack, but the m.p.g. is better & the power was increased by a noticable difference. srange to me to have a truck with over 1.1 mil miles perform better than when it had 400,000 miles.


but that is the case with mine. now I am afraid when the time comes for my overhead that if i take it in it will not perform as it is now.

I have a C16 600 ( turned up a little bit with PB power) and have it done every 100,000 miles. Even with the PB power I notice the difference in power but no drop in MPH.

I thought cummins factory recommendation was 500,000 miles? I remember reading that on their site, maybe that's the new ones.

Anyways, solo is absolutely right, if you noticed a loss, something wasn't done right.

There is more to the valve job then simply fuel mileage. Too tight and the valves hang open too long. This is especially bad for the exhaust valve, it can burn out. Too loose and the valve doesn't open enough, and it's hard on the valvetrain.

Actually Allan, I think you're right. I think that's why I was curious in the first place that the KW shop was saying I should get it done every 100,000 or so. I'd go look in my manual...but the truck's in the shop :roll:

I got mine done at my frth 2 days ago, its a 4 hr job, 575$ here w/taxxes.

I dont know anyone who paid what the Rev. said, all places that I have checked were over 400$...

Oh yeah, i went 252K miles and never done it, i gets 6.3 average for all the time used including idling.

Now, we will see..

Mine two weeks ago was $315.00. The one I had done last year was $284.89...at the same shop.

I just called Peterbilt in Green Bay, WI. 3 hour job, $250.

Thats a good price...

I've been at ALL dealers here and none have quoted me near that...

Detroit wanted 575$ before taxes and shop supplies.. :shock:

I love my Peterbilt dealer. They know me by name, their rates are reasonable, and my next oil change there is free. 8)

I called Volvo about having mine done. They said if it aint broke don"t fix it. No noisy valves no drop in fuel mileage. By the way I stay consistently @7.3mpg. Ved 12 motor 761K.

Had mine done at the Peterbilt dealer last Thursday and it cost $310

Left for California Friday morning and didn't notice much difference until I hit the mountains. Going up the grade it smoked like a freightrain on fire and started running hot. I had to stop 5 times going over Flag to let it cool off. Going down the grade my Jake brake wouldn't hold.

I called Peterbilt and gave them a piece of my mind and they told me to bring it in and they would have their real Cummins mechanic work on it. I said who did the overhead the janitor? They said just bring it in.

I am done with Peterbilt of Des Moines after tomorrow if they get it fixed.

I had always heard a overhead was only as good as the person who does it and now I know that's the truth.

Detroit seems to all be around that price. I don't know why, it only took about 3 hours for mine but they did replace my Jake brake spring.

They're crazy.