Strange Cam Spray Bar Issue

[rscheps]

While trying to diagnose a high oil pressure issue that has burst 2 oil coolers, I thought I would check the cam spray bars for blockages. I cracked open the upper rocker cover and could not see any holes at all in the spray bar.

Ok, no problem, the spray bar is just misaligned right? So, I was actually able to rotate the spray bar in place (should it be loose enough to rotate?) to make the spray holes point upward just like in all the pictures I have seen.

The trouble is, when I make the spray holes point upward at the intake rockers, the big holes drilled at the the ends of the bar for the cam oil line and for the cam tower plug are 90 degrees off and don't even come close to aligning with the cam oil line fitting. ??

If I align the big holes at the ends of the bar with the cam line fitting, the spray holes either point horizontally directly at the cam or horizontally at the outer face of the cam tower. That just can't be right because the intake rockers are dry either way.

The car is a 67 with original engine. Rebuild history is unknown but it runs well. Am I just dealing with incorrectly machined spray bars or is this normal for a 67?Any ideas appreciated. Thanks.

[4sd911]

I don't know if a '67 is different that latter towers but the spray bar should not turn, at the back of the tower there is a plug that has a tip that goes into the spray bar to hold it still. There are two areas on the bar that have holes to oil the cam and rockers, upward toward's the intake there is one hole per valve, downward there are two holes per valve. Rotate the spray bar so the one hole is pointing up and see if the large oil hole aligns with the oil line fitting. Sounds like the tower will need to come off to fix the tube. The early engines have different valve covers and towers might be a good time to up date with latter type ones so long as this isn't a concours car.

[MBruns]

Sounds like someone installed them backwards, if they rotate the locating pin/bolt is is not engaged, when they are put in from the factory they use a type of locite at the larger transfer holes in the middle of the tube, kinda of overkill.
Mike Bruns

[Walt Fricke]

If the spray bar is misaligned, the cam journals don't get lubricated!

I think you have an engine which needs to come apart before it decides to do it all on its own.

But you can pull the spray bars without much engine disassembly if you have it out of the car. The cam carriers have a plug on each end to seal the spray bar drilling. You can pull the ones at the flywheel end of the engine - just take off some sheet metal, and the oil cooler (you must be good at that by now). Pull those plugs, extract spray bars, and take appropriate action.

I wonder if these bars are broken? The flywheel end plug/locating screw, if screwed in tight, ought to hold a misaligned bar - by punching a dimple in it, as it is just thinnish aluminum. All sounds unusual.

There is only one proper orientation for each bar. They physically can be inserted end for end in two ways, and rotated 180 degrees, and the plug will engage its hole. But end for end wrong means at least one cam journal doesn't get oil, and upside down means the rockers and cam faces and springs don't get their proper oil. Upside down and backward, well I suppose that may be the worst.

I'd send a picture I posted a month or so back, but that computer is acting up. A search here will turn up the right information in some detail, I feel sure. Also how to pull them, and what to do to replug that hole (I tap with 1/8" NPT and install screw plugs, but most shops just buy or make new plugs interference fit plugs and press them back in).

[rscheps]

Thanks for the replies. I should have clarified that the threaded plug that keeps the tube from rotating was out when I rotated the bar.

Here is what has me stumped. When I open the valve cover and look straight down, this is what I see (pic below). No spray holes. In this picture, the holes are pointed horizontally right at the cams... But, the big hole at the end of the bar where the oil enters from the cam line is perfectly aligned. If i spin the bar 180 degrees, the spray holes point horizontally outward toward the outer wall of the cam tower.

It is pretty clear that it will have to come apart. The only conclusion I can come to is that the spray bar was mis-machined. That may be the cause of my high oil pressure too if the cam oilers are blocked because they are misaligned.

The real shame is that i will miss a big chunk of the very short driving season here in Cleveland.

I thank you and my engine thanks you.

[WERK I]

rscheps,
"Oil holes pointing up"? I don't believe that is correct. The picture below is from Wayne's archives when he was writing his 911 engine rebuilding book. This is the view you would have when looking down the cam tower with the intake valve cover off. I have verified this view of the spray on both 930 and 911SC engines. There are two more holes in the bar, one approx 90 degrees down from the hole you see and one about 120 degrees from the visible hole.
I don't think the problem you're experiencing is in the cam tower area, but more in the main oil circuit, i.e. the oil pressure relief spring area. I defer to the experts in the earlier vintages, but wasn't there a problem with these in the early engines?

[Eagledriver]

If your oil bars are truly misaligned you should see damage on the cam lobes and rockers. Assuming you don't then that's probably not the problem. Your picture looks normal to me compared to the other picture. In any case your cam lines have nothing to do with your oil pressure problem. I'd check the pressure relief and safety valves first.

-Andy

[4sd911]

I don't know this for sure but the early engines I believe have what is called "center oiled" cams made by solex, might not have the same spray tubes as in latter engines. Maybe someone with experience with the early engines is needed.

But this may not be the problem you are looking for with the high oil pressure. As stated above look at the pressure relief valve and the safety valve, the safety valve is to protect the oil cooler form high pressure.

[Flieger]

Yes, early cars had center-lubed cams. They soon went to the spray bar because the center-oiling was not adequate at the lower revs most street drivers drove at. The racecars were fine and continued to use it. The 935s had both center-oiled cams, oil spray bars, and some machine work on the head to get more oil to the exhaust valve guides.

[Walt Fricke]

Er, right - that would have been good to know, and we'd have steered you away from a blind alley.

From the looks of that picture, you do not, and did not, have a cam oiling problem. If you remember which way those bars faced before you, unfortunately, took out the locating plug, put them back.

The orientation of the sprays is not intuitive. The intakes (at least the ones which you see from the intake side) do spray sort of up at the valve cover.

In 1976 or 7 there was a change in how the oil from the pressure setting relief piston was routed. In your engine (when it left the factory), when that piston uncovers the relief hole, the oil dumps right back into the sump. In the later engines, that oil dumps back into the oil pump intake passage, ready to be pumped again, so less oil enters the sump other than through a bearing or squirter. Reduces windage. Not having that modification has nothing to do with excessive oil pressure.

I guess you don't know if it does or does not have this modification? It only matters because after the modification different pressure pistons were used, the regulation spring was longer, and had a short support tube inside its bottom end. Mixing old and new components could cause trouble. You can easily find pictures of each. If these pistons don't just drop out when you pull their plugs and springs, that could be the issue - the cylinder or piston may be worn and sticking.

I just went through a "why is my oil pressure so high" discussion with a fellow. Seems the cause (after investigating how the whole system works, and how a recent change to his sump plate could have nothing to do with the problem, but was the most recent change he recalled) was stop leak. He put a whole bunch in his oil to stop some small engine oil leaks. Said it worked, too. But it must have raised the viscosity through the roof. Problem solved there.

So when did your coolers start bursting? Engine run fine for a long time, then develop an issue? You did something to the engine (stop-leak??) to make oil a lot thicker?

If your engine oil thermostat has failed, it will put cold oil through the engine mounted oil cooler. Its function is to keep that cold, thick, higher pressure oil from being forced through the cooler. When the engine warms up a passage to the cooler opens. Thermostats don't last forever.

But that just might not wash - the cooler sees the same static pressure no matter the position of the thermostat. While it fails in the "cooler bypass" mode, no matter why the thermostat is in bypass the oil pressure reaches back into the cooler from the main oil system, so it always has system pressure trying to burst it. Just maybe not quite as much? And in bypass the flow restriction of the cooler with cold oil can't prevent that cold oil from doing its best to get to the bearings.

Luckily, you have carbs, so the thermostat is fairly easy to get at. Easy to test, too: put in your freezer for a while. Then toss in a pan of boiling water. If nothing moves, it is dead. Get a new one. Might be related to the bursting issue (or they are cheap replacements - just saw a different discussion on that).

How high is high? Only really high when cold? Drop to normal when the oil heats up? Got some pressure values to share?

Walt





Take out both of the pressure regulating devices. The key one is the vertical one, which sets the pressure. The piston should come out with it.

[Walt Fricke]

The production center lubed cams ended with the 3,069th engine off the assembly line. Thereafter they got spray bars. Not an issue for a '67.
(per Anderson - only Grady knows that kind of stuff off the top of his head)

[304065]

Well, the number of holes in the spray bar changed over time-- the number of holes was increased for the 1967 model year, by three- one more hole per cylinder.

Here is the description of the original holes: In the camshaft housings are aluminum tubes with holes, three of which are approximately 3 mm (0.12 in.) dia. through which the oil flows to the camshaft bearings. Six holes of approximately 1 mm (0. 04 in.) dia. , splash oil on the cam lobes. The remaining three holes allow oil to splash against the inlet valve cover in such a manner that it will drip down on the rocker arm and valve stems.

If you had a true centerlube cam box, not only is there no spray bar, there are no threaded bosses for the oil feed banjo bolt on one end, and plug on the other. The rib just continues down to the end of the box and terminates.

Walt, I don't have Dave's correlation chart handy, but the first spraybar engine is 903070, which is a late 1965 calendar year change during the 1966 model year.

[rscheps]

Here is the sad story of the oil coolers and how they led me to the spray bars.

The car came to me with a popped oil cooler. I put in a new aftermarket cooler which lasted about 6 months before leaking in the same place as the one before. (I was new to the sport at the time and didn't check everything I should have before replacing.)

After cooler #2 failed I replaced relief spring(short spring, no guide), downgraded from BP 20W50 to BP 10W30, checked the thermostat function in boiling water, and got very careful about warming it up before going above 2500 RPM. The third cooler rewarded me for all this effort by lasting about 2 weeks. This led me to look for blockages in the oil lines - can't think of what else to look at.

The oil pressure pops up to 100psi at almost anything above idle when cold. It idles at about 20psi when cold but jumps up fast right to the pressure relief - which makes me think flow restriction. Gage is an S-Gage newly rebuilt from NHS and sender is also new.

I am thinking the cam journal oil holes must be misaligned and therefore not flowing. If the crank bearings were blocked I think she would have blown up a year ago. Anything else I should be checking?

[Flieger]

Originally Posted by rscheps

...The oil pressure pops up to 100psi at almost anything above idle when cold. It idles at about 20psi when cold but jumps up fast right to the pressure relief - which makes me think flow restriction. Gage is an S-Gage...

Mine does the same thing. I thought that was normal. Warm oil pressure is ~12 psi per 1000 rpm- good.

[WERK I]

Don't forget the oil thermostat(circled in red)...... if it has failed, cool high viscosity oil will flow through the oil cooler and shorten its life in no time.

[Mr9146]

I've chased this same problem, too.

I checked/tested/changed every single thing I could think of that could possibly be related to excessive oil pressure ... relief valves, springs, spring caps, thermostat, oil filter, oil filter console, oil weight ... you name it, I checked/tested/changed it. The offending car had already popped two coolers and I didn't want a third to be wasted.

In the end I was unable to find the exact cause of the problem; a problem which materialized out of nowhere.

During my hunt I found that, upon removal of the sump plate, there were pieces of a previously broken chain rail still floating around inside the engine case. My hypothesis is that when the rail broke it got sufficiently chewed up by the chain/sprockets and a piece of debris must have lodged itself in one of the oil passages.

I have no resolution to report....

[Flieger]

Was that a customer car or was it one of yours, like the "Blue Dog"?

The engine ran fine otherwise (warmed up and in the powerband)?

[rscheps]

thanks all for the moral support and suggestions. I will keep looking for root cause.

[Walt Fricke]

Yes, if the crank (or intermediate shaft, or both) are not getting enough oil, you will have rod or main bearing failures. Temperatures will start going up, oil pressure will start going down (usually), and then things will explode or sieze up. A friend had a bit of O ring in his crank oiling passages. Starved one of the center rods. It was a Carillo, so all it did was sieze when he pulled off the track and stopped. Turned blue. His oil pressure never dropped even though there was little left of that bearing.

If you have inadequate oil to the cams and rockers, you get very accelerated wear. No oil on a cam and it will very shortly wear through the hardening, and then the rocker will machine the cam lobe into a nice circle. I saw one where on each side of where the rocker wore were two perfect thin slices of the original cam profile.

Another reason (beyond all that nice oil in your picture) to doubt your cam area restriction theory is the fact that on the 964s or thereabouts Porsche significantly reduced the diameter of the ID of the fitting where the cam oil line joins the cam housing. They concluded that way more oil than needed was sent to the cams. Lots of us (in my case, monkey see, monkey do) promptly put in the more restrictive fittings. So far (couple of years, some street miles, bunch of track miles), so good as far as not seeing excessive wear up in the cam area. But this did not overpower the normal oil pressure setting mechanisims, and in my case I can't say I noticed significantly increased oil pressures. Just having a bit less frothing around in the cam area was good enough for me.

You, like Marco, might start thinking of disassembling this motor. I can understand why you don't want to keep bursting oil coolers. He found broken parts in his sump. It is a bold person who runs such an engine for very long unless he knows just what the deal was .

You could rig up a remote oil cooler (with a pressure gauge maybe in that line) in place of what you have, and use a cooler rated for high pressures. Maybe put an electric fan over it for air flow. That way you could get to see what your pressures did when you got the oil up to 180F and above. But that would be tricky and maybe expensive. I think disassembly might be better, even if no part of the engine is showing apparent oil starvation.

Oil coolers ought to withstand 100 psi. In fact, you'd think they ought to hold 150 (if not, why does my Euro 911 have an oil pressure gauge which goes up to 150 (well, 140, but there is some space above that mark)? I'd be inclined to want a pressure test before purchasing a used one. This is done with a jig to plug one of the holes and allow an air hose to be attached to the other. Pressure it and put it in a bucket of water and see what bubbles out. Some of the sellers of used parts will do this for you.

Mostly, folks with older engines are worried about LOW oil pressure. Now several emerge with the opposite issue.

Both of the pressure relief mechanisms have a hole below the piston which allows any oil which gets by the piston to dump into the sump. If that hole were blocked (don't ask me how), eventually the piston would not want to depress - it would be basically hydrolocked. One might be able to check this by pulling the reliefs and running a wire up there and around corners and so on. A long shot.

If you do take the motor apart, in addition to pulling all the various oil gallery plugs and cleaning everything out, you ought to consider the revised pressure setting system. You can actually do it yourself with drill bits and a tap and plug, if you are handy. Or a shop can knock it out.

Nothing so simple as oil that is too thick, alas.

[rscheps]

Thanks Walt. I also don't understand why 2 new aftermarket coolers would spring leaks when the pressure gage never appeared to jump over 100 psi. Maybe the welds in the aftermarket coolers are just less durable.

I also don't understand from the description of the spray bars supplied:

The remaining three holes allow oil to splash against the inlet valve cover in such a manner that it will drip down on the rocker arm and valve stems.

My spray bars simply don't have above mentioned holes. Maybe the cams are flinging enough oil up there to keep the upper rockers alive - but there is definitely nothing spraying up there directly. I can actually run it with the upper covers off and I just get a few random splatters coming out. As they say in Texas: that ain't right.