4.0 Valve tappet repair

[Hurricane 4x4]

My girlfriend is looking at buying a grand cherokee, she found a nice 04 at a dealer with 46K on the clock but one thing worries me. On the service history it says "4.0 valve tappet repair" made under warranty at 30,000 miles. It seems kind of unusual for a motor that young to need any valve work. The thing is still under warranty, and i'm sure it'll be fine, but do any of you know if this is a common problem?

[hkszx2]

coulda just been an adj. made or someone broke a valve by beating it to hard

[dasVettemeister]

I wouldn't worry too much. Chances are it had a collapsed/noisy lifter that was replaced. It happens.

[J B]

Do those newer 4.0L engines still use a flat tappet, or are they roller? I was thinking they were still flat tappet.

In any case, for any of you guys that have vehicles that DON'T have roller lifters, you might want to consider running motor oil meant for diesels (Rotella, etc.). In recent years, all of the major oil companies have been removing additives from their motor oil. These additives were in place to prevent friction at the cam lobe/lifter interface, which was the highest friction point on the entire engine. The down side was that they were bad for engine emissions, since some amount of oil does wind up in the combustion chamber.

With rollers being in almost every engine these days, it's not much of an issue.....unless you have a non-roller engine in one of your vehicles. For whatever reason, the diesel oils still have the additives.

This has been a topic of discussion in the last year or two on some boards. I'd have to dig through my email at home to get some links with more detailed info, or you could probably google it.

[dasVettemeister]

Hehehe, my buddy found out about high-pressure friction additives the hard way a number of years back. Against my advice he decided to run aviation spec oil in his small-block chevy. Av-spec oil lacks the high-pressure friction additives that are needed and a couple thousand miles later he had flat cam lobes.

[nate]

So your going to run 15w-40 in a gas engine, J B?

[J B]

So your going to run 15w-40 in a gas engine, J B?

I would if I had anything with flat tappets, but i don't. It's not THAT big of a deal. You've got oil in weights ranging from 0W-30 to 20W-50 that are commonly available at any parts store, all meant for gas engines.

An email from a guy I know who works at Comp Cams:

Hey guys,


The information already provided is pretty much correct. As most flat tappet cams were replaced by rollers in the mid eighties, motor oil companies were able to refocus their attention toward other concerns such as friction in the rings and bearings as well as emissions. Therefore, many of the high pressure friction inhibitors have indeed been removed from passenger car motor oils without any negative effect on typical applications. However, the thing that has suffered from this is the break-in of flat tappets. After some research, we (Comp Cams) believed it prudent to recommend the use of oil with the friction inhibitors included. Because of the more severe loads in diesel applications, many of the better diesel use motor oils have high pressure friction inhibitors as good as or better than any of the "old" oils. The current API ratings to look for are CI-4 Plus, CI-4, and CF-4. A few readily available oils that meet these criteria are as follows:


Castrol Tection Extra SAE 15W-40
Chevron Delo 400 Multigrade SAE 15W-40
Mobil Delvac 1300 Super 15W-40
Shell Rotella T Multigrade SAE 15W-40


Oils that meet these standards should be used at the very least through the flat tappet break-in period, along with Comp Cams' Pro Cam Lube applied to the cam and lifters and Comp's Camshaft Break-In Lube oil additive.


After break-in, it is possible to go back to "regular" oil...but personally, I would keep running the diesel oils I mentioned above. The only drawback is that it is hard on the cats to be using diesel oil, but there are so relatively few cases of catalytic converters being used in a flat tappet application that no one has seen it necessary to come up with a solution for such a case.

[nate]

If there was an issue with regular oil, I'm pretty sure everyone would be having problems. It's only recently that roller cams... or motors without pushrods have become the thing to do.

I don't diesel oil is rated for use in gas engines. I'd have to look though.

[J B]

If there was an issue with regular oil, I'm pretty sure everyone would be having problems. It's only recently that roller cams... or motors without pushrods have become the thing to do.

I don't diesel oil is rated for use in gas engines. I'd have to look though.

No one is having problems because with very few exceptions, there hasn't been a car produced in 10 years that's had a flat tappet cam. Rollers hit the market mainstream 20 years ago. Not exactly recently.

But, LOTS of people are still building "older" engines for older cars and using flat tappet cams. Considering a roller cam setup for a small block chevy will run you over $1,000 easily, you can see why this is the case. That's why you see the email that I posted above. You've got warranty guys at Competition Cams that are VERY concerned about the lack of friction additives in oil.

And let's not bash pushrods. It may be "old" technology, but it works. A couple of the most powerful engines in mass production today are pushrod engines.

[CurtP]

Ugh - do we really need to get into another oil discussion? JB - I understand your concern, but I think you may be confused about what is happening with oil additive packages as a whole in the newer oil specifications. Responses from companies such as CC really don't help either - those bastards can't seem to get a cam right; what the fuck do they know about oil? As much as it pains me to say, bobistheoilguy.com would be a better source for oil advice.

I'll try to keep this as short as possible - oil companies are *NOT* removing anti-friction additives; they're changing them to align with new specifications. The new specifications are becoming more strict about the use of certain additives (usually for environmental reasons). The new specifications are also more strict about meeting anti-wear criteria and long-term OCI requirements. Today's new oils protect better than they did just a few years ago and there is no logical reason not a good quality modern oil from a reputable vender. Running a diesel-specific high-detergent oil isn't the best idea in a gasoline engine. What's more, those oils are changing to meet the new specifications as well.

Didn't I post about some of the changes to the new ILSAC GF4 specifications awhile ago? If you're really interested into the truth, then here's some links:

http://swri.org/4ORG/d08/GasTests/ilsac.pdf

http://api-ep.api.org/filelibrary/IL...v%20060104.pdf

http://swri.org/4ORG/d08/GasTests

Lubes'n'Greases magazine is a good source of information too: http://www.lngpublishing.com/subscribe.htm

[J B]

Bibistheoilguy is a total friggin' moron. His "tests" are about as accurate as a 6th grader could be doing a science fair project.

As far as the additives, this has come up because of flat tappet cam failures. If you don't have a car with an engine that has flat tappets, then it's not an issue. Since almost every vehicle that rolls off the line is a roller these days, the different anti-wear characteristics aren't an issue. If you're rebuilding the SBC in '78 Chevy, it IS an issue.

And I agree that running diesel oil in a gas engine isn't ideal, but faced with either that or wearing cam lobes, I'd run the diesel oil. It personally doesn't affect me since I don't have anything that's not a roller, but if I were to build a flat tappet engine in the future, I'd address that issue.

As far as oils meeting the API spec, an oil can meet the spec and still suck. I have seen the insides of hundreds of engines, and I can tell you in 3 seconds if the owner ran Pennzoil or Quaker State in an engine, simply by looking at the crap those oils leave behind.

Now, addressing the info from Comp Cams, you'll see that the first line of the email that I posted is:

The information already provided is pretty much correct.

The "information already provided" was a string of posts from a board where this had been discussed, full of references for all of this mess. I got it all in an email from a friend of mine. I didn't post the entire thing because it's really long, and it's all summarized by the email from Comp anyway.