The Stovebolt Site Forums The Shop Area Engine Shop Lost oil pressure!! ARRGGGH!!

Ship those parts off to Patrick. He's pretty good and won't do you wrong. Truckernix described the method I was thinking about, just didn't say it right. I'd recommend using either diesel or kerosene to flush, they have some lubrication in them. Bolt the oil pan back on and tow the old gal home. I think this fix is going to cost far more in labor than parts.

Chiphead, if you do get it going with decent oil pressure, it won't be anything you can depend on. It probably won't last long either. You know it's got to be torn down. I feel for ya. Mike

I am wondering if the oil pump lockdown-bolt was not drilled correctly(improper length from bolt hole to the dist. end of the pump). I see no way for the distributor(shaft & gear) to move down into the pump.Was there a spacer with the mini HEI distributor that was suppose to go between the block and the flange on the dist?(where it fits in the hole in the block)
Doing the flush on the engine MAY be ok,but I do not have my eyes there to see the bearings and the crank journals to determine how much damage was done.

Not "hell", things have just gotten really interesting. Mine went ka-flooey in ten minutes.

Persevere.

Mech, When I called Tom, we had a long discussion about the dimensions of the oil pump and HEI distributor shaft. All of the dimensions were correct except for the recess in the top of the pump, mine is about .050" deeper than the one Tom was measuring. We did not check the dimension between pump surface and bottom of drive tang slot. The spacer gasket between dist and block was present, the pointy bolt was correctly installed, the distributor was clamped down properly.

Engine failure analysis is difficult, its hard to parse out the cause-effect relationships in something like this. Would the metal removed from the oil pump be enough by itself to eat all the bearings? Was the oil pressure failure caused by a sticking relief valve, or a wiped bearing? I find it hard to believe that the engine bearings failed from improper clearances or dirt introduced during assembly. I plan on talking to the shop that did the machine work, and see if they have any insight.

If I flush the engine with diesel, will the diesel keep the internal parts from rusting until I replace the oil pump & parts?

Here is my plan so far: Get the car home & put up on jackstands. Flush the engine with diesel and clean it out. Plastigauge the main bearings and check the cam. Check the plastigauge results with what the clearances were during assembly. Replace pump, pickup and distributor gear. Run engine and change oil a few times. If the oil pressure holds, great! If not, the next part I'll buy for the car will say "for sale".

chip

I left the oil pan off quite a while after flushing with diesel and noticed no rust at all. And it rained.

According to my shop manual you can't plastigauge with the engine in the car.

Really? I figured I could wipe the oil off the journal & get some fairly accurate measurements. I plan on checking the #3 thrust main next, as it tends to take the most abuse and show the most wear. If it looks good, I'll feel much better about flushing & saving this build.

Anybody take a look at those pics? Whaddaya think? Did the gear chew the pump, or am I imagining things?

thanks yet again....
chip

Chip,
there is a procedure for using plastigage on the mains, with the engine in place. What you have to do is use a jack to push up on the crankshaft slightly to take the weight off the bearings. This is mentioned in either the GMC or the Chev manual. I don't think that there is going to be a change in clearance that soon, unless there is visible obvious damage.

I had a look at your pictures and they are nice and clear. However, I don't understand where all the damage is. Are there chipped teeth in the photos, or what? If the gear is damaged, you will need to look at the cam gear too.

Look at the close shot of the top of the oil pump. Does that recess look like the bottom of the gear chewed into it? Also look at the close shot of the distributor gear. Examine the shiny face of the gear tooth. Does that look badly damaged?

Boing!

Got new melling pump in from NAPA. The top of it has 'no' recess like the pictures I posted above. Its totally flat except for the hole that the distributor shaft goes into. What is a Melling M45 pump supposed to look like?

Can I swap the dist gear from an old stock 235 distributor onto the shaft of the HEI unit?

thankx yet again
chip

That's what you pump should look like before the distributer grinds it up. The stock 235 distributer shaft is .490 diameter as is the 230-292 shafts,measure yours.Check the installed gear position against a stock points distributer.That HEI may still be suspect, check the fit out from all angles.

I'm coming in late on this saga but I would definintely agree with Tony that your distributor is still suspect! Don't just swap out the gear without comparing the whole thing to another unit.

I got under the car last night and poked around for several hours. The main bearings show fine scratches from metal, but are otherwise OK. Crank journals are not scored or blue. Crank endplay is fine.

Cam lobes & bearings look OK. It was very hard to examine the dist drive gear on the cam, being upside down under a car and all. It looks like the drive faces on the gear teeth have taken some abuse, but I don't know how severe it is. Do I have to pull the cam whenever gear wear is suspected?

I mocked up the pump and distributor and examined how it fit together. It seems that the distributor may be at fault, even though it seems to have the same critical dimensions as the stock distributor.

I may be dealing with a complex issue, where distributor shaft end-play, combined with the block dimension of dist mount to oil pump mount caused this. Why else would this dist work in a '54 engine, and cause a problem in a '60 engine?

Also, does the oil pump body supply any lateral support to the distributor shaft? The stock shaft fits snug in the oil pump, where the HEI shaft only contacts the pump at the drive tang.

ideas? observations? insults?

chip

Chip, the block supports the distributer. By any chance, did you or the machinist remove the the block mounted bracket that supports the oil pump? . Either run a stock type distributer or remove locating flange on that mini HEI.Then use a clamping system similar to stock.No chance of the distributer being forced into the oil pump by the hold down clamp.I used to modify quite a few 250 style HEI's for use on 235/261's.A hold down similar to the stock one never caused a problem.

Talked to Patrick today. He told me to talk to TomL about his mini HEI. TomL and I went over all of the critical dimensions of the mini HEI, and all of them were in spec. So TomL says its a fault of the oil pump or engine block.

TomL says the top of the pump takes the dist gear thrust, and that if there was a problem it was due to the oil pump allowing the dist gear to fall below the centerline of the camshaft gear. Then the camshaft gear forced the dist shaft into the pump harder than normal.

Both Patrick and Tom questioned me about the oil pump mount, and if it had ever been removed. AFAIK, it has not been tampered with. Both agree that if the oil pump mount is ever removed, the block is ruined. The factory installed a rough casting there, then broke off the bolt heads on purpose. Then a special boring machine would line-bore the block and oil pump mount holes true. The after the deburr operations, the block and oil pump mount are mated forevermore.

One thing TomL mentioned is to check the alignment of the oil pump mount by using a new oil pump and my existing HEI dist with bad gear still installed. Put some prussian blue or layout red on the bottom of the gear and install in engine. Rotate motor while pushing down on rotor to assure contact between gear and pump body. Remove distributor and examine the top of oil pump for even contact between gear and pump. This will show if the block or pump body is somehow out of line.

TomL seems to think that a new pump and dist gear will get her running again, as long as there is .010"-.050" installed endplay between dist shaft and pump casting, and dist gear centerline stays above cam centerline.

This is so weird. Can anybody make sense of this?

chip :confused:

I can tell you that on my 51 216, the oil pump does not take up end thrust from the distributor. In fact I doubt that the oil pump is made to take that.

Is there any chance that the zero oil pressure reading caused you to find an existing unrelated problem?

Not really....

However, I'm one of those guys that real mechanics hate!



It sounds like you've probably saved the engine from destruction, so I would figure out some way to shim that distributor up very slightly to give you some clearance. If you don't have any more grinding metal you might be lucky this time. So far this whole thing doesn't make sense to me....

:confused:

Was this engine running before you rebuilt and upgraded everything?

I bought this engine for parts in the early '90s. The engine was bone stock, covered in crud but would run. I took it apart to cannabalize it for parts. All the sheetmetal got lost except for valvecover. Oilpump, pickup, distributor-gone. My dad threatened to throw the block away, so I had it at college as a TV stand. So all I had was the bare block when I needed a new 235 last year. Lucky, I still had the '60 block.

So I rebuilt it completely, reused my '54 head & crankshaft. All other parts are new, even the rods are reconditioned. I did the initial break-in Dec 1, 2002. It runs 150 miles, then the oil pump pops the weasel superbowl sunday.

Should have left this engine under my 19" Zenith. :mad:

What do I do now? Change the dist gear? Change the dist? Pull the cam? Give up?

If I had known this thing was going to be such a malfunction junction, I would have torched this I6 crap out and used my Poncho 400 w/TH400 tranny.

chip

We might have to start a "Save Chip's 235" parts fund for ya. lol. Have you been over to http://www.inliners.org

I joined when I got my 235. Maybe someone has seen a similar problem.

Give up? Hell no - fight back! You've got 3000+ folks here dying to find out what the problem is. Get in there and start measuring and ciphering. You'll win.

Hey Chip seems I have the same set up as you 60' 235 with melling pump, Tom's HEI, Patrick's M4F cam, dual rochesters, Fenton's, full presure oil filter etc. Last week I primed system with drill in pump. Before doing so I pulled dist and checked what I could, found that dist set up about 3/16" before droping into pump slot and seating in block. No wiring so I used jumpers and a hot wire, went right off. Good pressure, sounded good, smoke smelled great (inspiration). Could only run several minutes as no radiator mounted yet. It does juice yah up to get cranking and get it done, but long way to go. I'm watching this post to see if I need to make any changes. Zeke

Hey Zeke,

After you do the initial cam break-in, pull the distributor and check the gear for wear, and look at the top of the oil pump for contact or wear. Let me know what you find.

thanks
chip

I don't know much about the later 235's but there are some differences beteween a 54 and a 60. Don't the 54's still use shims on the mains and could there be a difference in distributors,cams or cranks?

Cam, cranks & distributors are supposed to be the same. The '54 and '60 engines did use a different oil pump, but I think the differances are in the cover plate. Don't know if there are any dimensional differances at the top of the pump.

Nope. Never give up. Never let a hunk of metal beat ya! You hafta learn to outsmart them....