Northstar Camshaft Wear - Common? Cause?
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Northstar Engines and System Technical Discussion Discussion, Northstar Camshaft Wear - Common? Cause? in Cadillac Engine Technical Discussion; New member here. I hope this topic isn't already covered. If it is, I apologize. I have seen Northstar engines ...
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    Mark D is offline Cadillac Owners Member
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    Northstar Camshaft Wear - Common? Cause?

    New member here. I hope this topic isn't already covered. If it is, I apologize.
    I have seen Northstar engines with this same symptom, and am wondering about it. I'll get into why I'm wondering in a minute.
    It seems that the exhaust cams wear dramaticallly, showing both lobe wear and tappet wear. But not on all lobes and not on all tappets. It seems to usually be the tappets toward the middle of the head that show the most wear. Yet, these engines were, and are, perfectly good running engines. Were it not for my being aware of this wear, I'd think the engine was in great shape.
    The intake cams don't seem to have this issue. Strange, isn't it?

    I am currently doing head gaskets on a 98 Northstar engine, and it has this, what I see as, typical cam wear. This is my wife's car. I did head gaskets about 7 years ago, knowing that I'd probably have to do them again at some point. At that time, there was no really good fix for the bolt problem.
    This time, I'm using studs, and it shouldn't be a problem anymore.
    Last time I did the gaskets, the car had less than 100 K miles on it, and I did not notice much lobe wear. This time, it has the lobe and tappet wear I mentioned.

    Yet, if the head gaskets hadn't started to leak again (three bolts came out with the aluminum threads still stuck to the bolts - no surprise) I would have expected this engine to run indefinitely.
    It looks like iminent cam failure. But is it? Is this a sort of normal thing that I can just ignore rather than have to spend 800 bucks on two new exhaust cams?
    That is my question. Just how serious is this really? I'm thinking of replacing the right side cam with new, and let the front go because it wouldn't be too difficult to change with the engine in the car.
    Wondering if anyone has any helpful comments on both the cams, and my plan.
    Thanks so much. I should add that the car now has a little over 200 K on it.
    Mark D.

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    Re: Northstar Camshaft Wear - Common? Cause?

    Before 2000 the Northstar engines used flat tappet type cam followers. This type of cam followers wear out with today's oil with less ZDDP/anti-scuff package in it.

    This is the main reason why many members here will suggest to use a HD/Diesel rated 10W-30 to your 99- and before Northstars. These oils carry higher anti-scuff/anti-wear package and perfectly OK to use diesel rated engine oil to a gas engine. They do not have those "starburst" logo because it will not meet the environmental reguations. 00+ went with roller cam followers and do not suffer these problems.

    Make sure you are using a 10W30 too. No fancy oils like 20W50.

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    Re: Northstar Camshaft Wear - Common? Cause?

    Yet, if the head gaskets hadn't started to leak again (three bolts came out with the aluminum threads still stuck to the bolts - no surprise) I would have expected this engine to run indefinitely.
    It would have if you had used inserts or studs the first time.

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    Re: Northstar Camshaft Wear - Common? Cause?

    Quote Originally Posted by Mark D View Post
    New member here. I hope this topic isn't already covered. I
    It seems that the exhaust cams wear dramaticallly, showing both lobe wear and tappet wear. But not on all lobes and not on all tappets. It seems to usually be the tappets toward the middle of the head that show the most wear. Yet, these engines were, and are, perfectly good running engines. Were it not for my being aware of this wear, I'd think the engine was in great shape.
    About 20 years ago, I had a 1972 Vette that I'd done a considerable amount of work on.....Doug Nash 5 Speed, ported & polished heads, MSD, headers, intake, cam...you name it.....

    The cam was of a longer duration and higher lift than stock, so the car had a little bit of a "loppy" idle.....
    While doing some other work on it, I hooked it up to one of the better engine analyzers of the day....one that shut down individual cylinders and compared the drop-off in RPM's.....all of my cylinders had almost identical drop-offs at idle....except 1......it had a MUCH higher dropoff.....meaning that cylinder was MUCH stronger than the others.....at idle......about the same at midrange.....and much less at the upper RPMs....
    I took the engine apart....and guess what...the cam lobes on THAT CYLINDER ONLY (may have only been one lobe....don't remember if it was exhaust or intake) were trashed, along with the lifter(s).

    The moral of the story? An engine designed to run at lower RPMs will typically have a much shorter duration and a lower lift than a high RPM engine. This means when you lobes wore down, they may have even HELPED off-idle power/torque....but at the expense of higher RPM power.....and if your car is like most Cadillacs, it doesn't often see north of 4000 RPMs......

    Makes perfect sense to me!! And my 72 Vette? I ran a new oil in it....only the best!!!! Mobile One synthetic.....oooopppppssss....and until coming to this forum again after a break of 5 years, that's all I ran in my 97 STS....and yes, I had a couple worn lobes...

    Not sure that it matters, but The exhaust valves do get hotter than the intake valves....and may transfer some of that heat to the lifters....which may cause what little anti-wear protection the new oils have to break down quicker on that surface....

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    Re: Northstar Camshaft Wear - Common? Cause?

    Well, I have known about the oil problem for a long time. But I associated it with high performance engines with high lift cams and king kong springs. I just had this idea that an engine like this, with featherlight springs and low lift would do just fine. I've been running 10W-30 Valvoline Max Life summer and 5W-30 winter. I think I'll switch over to Brad Penn oil. It's not cheap, but it's the best bet of them all.

    And with regard to hindsight in inserts and studs; At the time, there was no information that I could find with regard to studs. Inserts were pretty much using the factory inserts. I had just come off a similar engine that had to have inserts. The common knowledge at the time was that when the inserts pulled out, and they often will, the block is junk because there's no fix for that.
    So, inserts were considered a repair for stripped threads, not something to do as a precaution. The heads seemed to torque up just fine. But the problem is, when you're using that stupid torque angle procedure, and you're turning the last few degrees on the bolt, you really can't tell if the bolt threads are climbing over the block threads or tightening. You're just turning until you reach your magic number.
    This time I am using the studs from Northstarperformance. They go to a 5/8-11 thread. They send a killer drilling/tapping jig along with the studs, drill and tap. If anything goes wrong, I have a spare engine around I can use the block from. I don't expect anything to go wrong, but it always can. It's really not as simple a procedure as it might look like. Extreme care is required.
    And, as far as running a long time if it hadn't blown the gaskets again, from what these cams look like, probably not. I'd still have had to deal with this.


    So, my question is, how many Northstar engines are running around out there with close to 300K miles and have well worn tappets (followers) and just keep on going? I hate the idea of spending roughly $400 X 2 on new camshafts if these will run another 3o to 50 thousand miles. By that time, my wife will have long since killed the car anyway.
    So what is the experience with this problem among those who have maybe disassembled engines with far more miles on them?

    Worse, she's driving my '95 until I get this done! And that car, to me, is a keeper. It probably has exhaust cams that look just like the others. All worn out lobes and tappets. But it's quiet and runs perfectly. And has never needed head gaskets. Yet.

    Did I mention that I really hate doing this job?

    Mark D.

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    Re: Northstar Camshaft Wear - Common? Cause?

    Well I think I know why the exhaust wears out but the intake doesn't. Or at least not as much.
    I took a look at the cams. The exhaust cam has a much steeper ramp angle than the intake, which has longer duration. This puts considerably higher stress on the nose of the cam lobe and the lifter. That part's solved. Still to come is how far it'll go.
    I'm going to install a new exhaust cam on the right bank because it's pretty tough to change that one with the engine in the car.
    The left bank still isn't exactly easy, but it's nothing like changing the right bank exh cam.
    So I'm going to leave the left cam as it is and see how far it'll run before it goes flat. I just have to know, I guess.

    Later on today I'm going out to buy a well used, poor condition, '95 Seville SLS that a guy's trying to dump and nobody will buy.
    I'll let my wife drive that until I get her's back together again. Waiting for parts will make this job last at least two more weeks.
    After that, it'll become a parts car.
    Mark D.

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    Re: Northstar Camshaft Wear - Common? Cause?

    Quote Originally Posted by Mark D View Post
    Well I think I know why the exhaust wears out but the intake doesn't. Or at least not as much.
    I took a look at the cams. The exhaust cam has a much steeper ramp angle than the intake, which has longer duration. This puts considerably higher stress on the nose of the cam lobe and the lifter. That part's solved. Still to come is how far it'll go.
    I'm going to install a new exhaust cam on the right bank because it's pretty tough to change that one with the engine in the car.
    The left bank still isn't exactly easy, but it's nothing like changing the right bank exh cam.
    So I'm going to leave the left cam as it is and see how far it'll run before it goes flat. I just have to know, I guess.

    Later on today I'm going out to buy a well used, poor condition, '95 Seville SLS that a guy's trying to dump and nobody will buy.
    I'll let my wife drive that until I get her's back together again. Waiting for parts will make this job last at least two more weeks.
    After that, it'll become a parts car.
    Mark D.
    Just so you know....the exhaust cams from the 95 SLS are the same as your 95 and 98 STS exhaust cams....

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    Re: Northstar Camshaft Wear - Common? Cause?

    Quote Originally Posted by Mark D View Post
    So, my question is, how many Northstar engines are running around out there with close to 300K miles and have well worn tappets (followers) and just keep on going?
    We have seen pictures in here of pre-2000 followers that have actually been worn to the point that the valve tip is sticking through the bucket. Earlier this year and more earlier than that. Needless to say, the associated cam lobe(s) were also trash.

    Flat tappet wear is not restricted to Northstars, though..........and, for what they are, they still run decent open spring pressures and lift measurements.........but the 4 valves and pent-roof semi-hemi chamber design don't need radical lift numbers.

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    Re: Northstar Camshaft Wear - Common? Cause?

    Thanks on the info about the cams on the SLS and the STS. Only thing there is that that SLS is so well used that I don't hold much hope for those cams being in very good shape.

    I found this site - Maybe you long time people already know about this. Called Cadillac Hot Rod Fabricators, or CHRF. http://www.chrfab.com/cam_shafts1.htm That link goes to their own camshafts. I can buy four from them for about the price of 1 1/2 cams from GM. They make some claims, maybe inflated but maybe not. They show a line of cams that don't specify any lift, but show durations (probably intake, they don't specify which cam has what) that range from 272 degrees up to 310. I haven't a clue what the original cams are, so I can't compare. But that 310 looks interesting. I have no plan to use it in this application though.
    They also sell new springs, and understandably. According to them, the stock seated pressure is 48lb for the 275 hp and 59 lb for the 300 hp while theirs is 100 lb. And for what they call factory lift, the same figures are 98 lb, 109 lb and 180 lb. I'm sort of thinking about their 272 degree cams. Probably won't go that route though.
    With regards to the spring pressure comment I made in an earlier post, I was not knocking the spring pressure on the Northstar engine, it is what it is and that is what it needs to be. I was only commenting that originally I was sort of surprised to see that sort of wear with such low spring pressure. However, with a lobe like that exhaust one, I can fully understand. I'll just use better oil from now on. Interestingly, I have a pushrod engine I built for racing back in 1982 that I raced for 7 years, then stored for about ten years. Then I needed an engine for a Suburban, thought of that engine, stuffed it in and am still running it. Interestingly, though it has a fairly high lift cam and, though I forget the original spring rating, roughly 250pound springs, and I'm using whatever oil I can find in it because I don't care much about it anymore, that old girl just keeps on going and going with no indication of cam trouble. I have put a little over 85000 miles on it since the racing (oval track) and storage. Some engines hold up with the "crappy" oil we have today, and some don't. I think these Northstar engines do fairly well, as I don't see much wear until they have fairly high miles anyway. Most people throw their cars away by that time, don't they?

    Oh, on that SLS, it's shot. Engine drips oil from everywhere, and only showed a bit on the bottom of the stick when I looked at it. That oil was pure black. Windshield is cracked, interior is worn and parts broken or missing, dents, typical salt rust, horrid looking wheels, tires pretty well used up, and worst, it had a list of codes so long, like every PCM code there is (just about) There were so many I didn't bother to read them all. I just cleared them and decided to see what comes back. They were all in history, not current. I'm going to look at it again today and make up my mind. It's cheap. It runs. It has a Northstar engine that can be parts or used elsewhere.
    Mark D.

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    Re: Northstar Camshaft Wear - Common? Cause?

    CHRFAB has been posted, discussed, talked about, tried many times in these threads. They do some neat stuff for stand-alone managed Northstars in Fiero kit cars and sand rails. Practically nothing for our PCM-managed FWD drivetrains. If you take their "270" cam specs at .006" lift and compare them to the same cam at a running timing check of .050" you'll see that they're nowhere near radical - a nice, manageable street re-grind.......and our 1998+ PCM's can't take advantage of the cam possibilities, so we're back to Square One.

    All this was discussed at great length, with posted timing cards and sprocket moving discussions last spring. It's all still in here somewhere. One of our members, AJXTCMAN, a Cadillac Tech, has done a slew of work on the northstar ECM's and PCM's and has come up with precious little for the 1998+ PCM cars. I believe that he is now involved in a side enterprise, pcmcalibrators, that is doing work on pre-2000 electronics. AJ has done some cam work.

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    Re: Northstar Camshaft Wear - Common? Cause?

    Thanks for the reply. Funny you should mention reground cams. Just today I started thinking about doing that with my cams, after finding someone who I believe can do it right.
    Also found an oil additive that should allow me to continue to use off the shelf motor oil but without the cam wear. I'll post more on it when I get my info together.

    Mark D.

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    Re: Northstar Camshaft Wear - Common? Cause?

    This stuff? ZDDPLUS


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    Re: Northstar Camshaft Wear - Common? Cause?

    You can also take a look at the Joe Gibbs Racing and Edelbrock websites - for HD oil formulations. BUT, be careful: indiscriminate use of oil additives and dedicated high load ZDDP oils will ruin a catalytic converter.

    For an "off the shelf" conventional HD oil that is satisfactory and safe for your two pre-2000 Northstars, simply shift to Shell Rotella or Pennzoil LongLife 10W-30 oils.

    If you're a synthetic oil person, another way to skin the cat during an oil/filter change is to blend in a quart or two of a EURO spec synthetic oil or a Joe Gibbs HR synthetic 10W-30 - both types have an increased ZDDP load and the blend would not exceed the older SJ or SL oil specification for additives - that spec was perfectly OK for catalytic converters 10 years ago.

    Google "api motor oil specifications" and open the Wikipedia page. Deep reading...............

    Go to www.joegibbsdriven.com , open the home page and click on the "Training Center" tab. Read the articles in the left column.

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    Re: Northstar Camshaft Wear - Common? Cause?

    Well, I'm still looking around. No rush, and that's good because I'm pretty busy with work.
    But so far, I'm looking at a product called Oil Extreme http://www.oilextreme.com/oil1.html
    It is recommended by David Vizard, and that's a plus. Not sure about how it might affect a catalytic converter.
    It seems to me I read that even the diesel (Rotella included?) oils are also sans the zinc whatever stuff that the EPA decided was a bad thing, thus are not as good for flat tappet cams anymore as people might think. That's what keeps me away from those oils. Otherwise, I could use a 5W-30 Rotella, if I can find it. I usually only see it in heavier grades. No, I can't use 10W-30 in winter. I do need the car to start, and even if it were to start with 10W-30, the bearings wouldn't last too long. Sometimes even 5W-30 is a bit too heavy and I wish I was using 0W-30. In summer, 10W-30 is fine. I change to that in summer.
    Otherwise, Brad Penn is excellent oil and shouldn't be a problem with a catalytic converter, AFAIK. I can get that locally, though expensive. But what oil isn't expensive anymore? :-)

    Also, with regard to regrinding the cams, I'm looking at having a well known cam grinder, Mike Jones, grind them. He says he's reground a lot of Northstar cams. No problem, apparently. I was worried about loss of base circle and lifter contact. But I guess that'll all work out fine. Still looking into that, too, though. No final decisions yet.

    But the block is drilled and tapped. It's waiting for me to get some gaskets. I've put it back on the "shelf" again for a while. Work comes first.
    That's why I bought that crappy SLS. Gives the wife something to drive while her beloved red STS sits up in the air with all its guts ripped out of it.

    Later
    Mark D.

    I should add, I can't really go to a lot of web sites to read information that I should read because I'm on a realtively slow dial-up connection. It takes to darn long to do that. I can leave my machines out in the shop for a short time, but not long enough to check a lot of links. The wikipedia link above is one that I'll read. I know I need to know more about the current oil situation. All I reallly know is that it's not good for some applications.

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    Re: Northstar Camshaft Wear - Common? Cause?

    No, I can't use 10W-30 in winter. I do need the car to start, and even if it were to start with 10W-30, the bearings wouldn't last too long.
    Where in the world did you get that idea from?

    The Northstar was tested with 10W30 in Kapuskasing, Ontario at -40F. I have yet to use anything but 10W30 (in this or any previous car). Starts and runs just fine even in below zero weather. 91,000 and counting.

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