Does cam have to go when DOD is removed?
07-09-2020, 06:12 PM
#1
Does cam have to go when DOD is removed? I have an 09 5.3 truck with DOD I'm installing some ported heads and 1.85 Comp rockers I'm not planning one a cam swap, but a lot of people HATE DOD What is so bad about DOD? Mine rarely goes into DOD 4 cylinder mode I'm told I have to swap the cam if I get rid of the DOD. Is that true? Why does the stock cam have to go if DOD is eliminated?
07-09-2020, 06:42 PM
#2
TECH Senior Member
The 8 DOD lobes and lifters are different from the 8 normal ones. If you go to all non-DOD lifters, a conventional cam should also go in.
Our Suburban has DOD and 140k miles with no trouble. You likely won't either, but many have.
You can tune it out without changing the parts but if you change lifters, the cam should also be changed out.
Our Suburban has DOD and 140k miles with no trouble. You likely won't either, but many have.
You can tune it out without changing the parts but if you change lifters, the cam should also be changed out.
07-10-2020, 07:23 AM
#3
Just to reiterate and expand a little on what G Atsma said, the lifters and lobe profile are different on the 4 cylinders that DOD is active on. The biggest issue with DOD engines seems to stem from a lack of routine maintenance. If oil is changed regularly they seem to go for quite some time/life of the vehicle. If not a lifter can fail, lots of times the DOD lifter fails in the full collapsed state and produces a dead miss. We have a truck in our fleet with less than 100k on it that has a failed lifter in it, sounds like complete **** when it fires up, as long at the roller on the lifter hasn't failed or turned in the holder, it could be changed out with no ill effect. I did a DOD delete on my new to me 08 Sierra a few weeks ago, truck has 188k on it, wasn't amazing inside the engine, but also hadn't failed so it's all kind of luck of the draw.
07-10-2020, 11:53 AM
#4
If you do the 1.85's you're gonna need some serious valve springs. Those rockers and valve springs will put a lot more load on the lifters and I would imagine a DOD lifter isn't going to handle that very well. May, may not. Don't really know since nobody really ever does this.
You have to run the lifters and cam that go with each other. If you have the DOD cam you have to run the DOD lifters. If you have a standard cam you have to use standard non DOD lifters.
You have to run the lifters and cam that go with each other. If you have the DOD cam you have to run the DOD lifters. If you have a standard cam you have to use standard non DOD lifters.
07-10-2020, 06:17 PM
#6
DOD lifters tend to fail, which is why people don't like them. And I've heard they don't work with over .500" lift (believe it's spring related). Note, even the L99 is limited to .500" lift compared to it's LS3 cousin with .551".
07-10-2020, 06:47 PM
#7
Most DOD issues stem from poor maintenance practices. The activation and deactivation of the lifters is controlled by an oil manifold system underneath the intake manifold. There's a small filter in that manifold that can become clogged on high mileage engines. There's also a pressure relief valve located near the oil filter housing that controls the pressure to the DOD lifters. The system operates within a specific oil pressure range of 27-66 psi with a minimum 22 psi to release the locking pins. Any issues along this system could cause issues with the DOD lifters that may not be related to the lifters themselves. I've seen several cases where the lifters are replaced only for it to have the same problems. Melling issued a bulletin better describing this in more detail.
https://www.melling.com/wp-content/u...s-3.1.18-1.pdf
Use a good oil and change it regularly, but more importantly, use a good air filter. Notice I didn't say oil filter but air filter. The best oil filter is a good air filter. This is because most air filters are 95-99% efficient @ 2 um (except for K&N and other "lifetime" filters) as opposed to the best oil filters out there (Amsoil Ea, Fram Ultra) at 99% @ 20 um. An air filter with poor filtration will let more dirt (silica) through the filter which then finds its way into the oil via the PCV system. At <5 um in size, it passes right through the oil filter and guess where it ends up? Yep, the DOD lifters and the manifold system supplying the oil to them. The K&N drop-in filters, along with their cone filters and other similar filters, have notoriously terrible filtration efficiency which shows up in used oil analysis as an increase in silicon contamination and often an increase in iron wear from abrasion.
If you want to delete the system anyway, you would want to change the cam at the same time.
https://www.melling.com/wp-content/u...s-3.1.18-1.pdf
Use a good oil and change it regularly, but more importantly, use a good air filter. Notice I didn't say oil filter but air filter. The best oil filter is a good air filter. This is because most air filters are 95-99% efficient @ 2 um (except for K&N and other "lifetime" filters) as opposed to the best oil filters out there (Amsoil Ea, Fram Ultra) at 99% @ 20 um. An air filter with poor filtration will let more dirt (silica) through the filter which then finds its way into the oil via the PCV system. At <5 um in size, it passes right through the oil filter and guess where it ends up? Yep, the DOD lifters and the manifold system supplying the oil to them. The K&N drop-in filters, along with their cone filters and other similar filters, have notoriously terrible filtration efficiency which shows up in used oil analysis as an increase in silicon contamination and often an increase in iron wear from abrasion.
If you want to delete the system anyway, you would want to change the cam at the same time.
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