[tgx]

Hello all,

Just wanted to share with you an issue I am seeing on my SBC 283.
I am in the process of pulling the oil pan to get at the pump but thought
I'd drop a note an get some opinions.

On this particular engine when there are sustained rpms of say 4,000 for a distance of 10 miles the oil pressure starts to do crazy things. NOrmally the engine oil pressure is solid at 40PSI unless stopped at traffic light where it dips to around 20. The first time I had a problem was driving about 65 for 10 or so miles and suddenly the pressure started pushing 80 psi. I didn't think much about it other than, 'Well I have great pressure.' When I came to the next stop though, the oild pressure dropped to 5psi and I got a 'knock knock'. I pulled into a service station and discovered oil had been dumped out all over under the hood. I cleaned it up best I could, refilled it with oil and drove back home. The kicker, I didn't use a drop of oil on the way home. I have no idea what happened, but it looks like it shot out of the oil pan seal near the front of the engine. I added some sealant and tightened the pan and haven't had an issue for almost a year. I don't regularly get it out on the interstate because the car is geared low and to keep up with modern day traffic I have to run those higher rpms which I don't like to do. At any rate, last weekend I again found myself on the interstate and as per above, things got crazy again. This time the oil pressure fluctuated from 40 down to 20 back to 40, down to 30 back to 40 with the engine making an odd surging, eventually I heard what I believer was cam and lifter noise and I immediately keyed the engine off. After coasting to the shoulder I got out and inspected under the hood. No oil blown out, so I checked the oil level. Oil level was fine. I scratched my head for a minute, got back in and keyed on the car. It started fine and oil pressure was again back at a solid 40psi. I drove the rest of the way home without issue. WTF? Does this sound like an oil pressure relief valve issue or possibly a high volume pump with too small sump issue? Misplaced oil pickup? It only acts up on the interstate which like I said I get on maybe twice a year.

I plan to change the pump as a matter of course, have a look at the intermediate shaft and the pickup depth, but other than that I'm out of ideas.

I should mention my oil pressure gauge is mechanical capillary tube fitted near the dizzy.

 

[cobalt327]

There's a chance the oil pump pick up is positioned either too close to the bottom of the pan or too high. Either will be made worse by a HV pump, IMO.

If it's too low (depending on the type of p-u you're using) the pan can actually get pulled up against the p-u. That might also account for the rise in pressure. Most any p-u if too close to the bottom can cause the pump to starve and/or cause cavitation.

If the p-u is too high or one end is tipped up and isn't sitting about level w/the bottom of the pan, AND the oil level dropped because the oil wasn't draining back to the pan faster than it was being pumped out during sustained "high rpm" driving, it could pull air into the pump.

Are you using a spin-on oil filter? If so, is the filter mount bypass valve blocked or open? There's a chance the oil filter might be collapsing or the oil pump pressure regulator valve could be hanging up or its spring could be bad, but I'd expect it to continue to cause grief even at around-town speeds if that were the case, but it's something to look at.

 

[tgx]

First things first

Okay, so I drained the oil and removed the filter and discovered the oil spin on adapter has this written on it:

Use the large holes only for 393, 427, 454 CU Engine

Unfortunately the large holes seem to be in use and the engine is a 283 cid.
Not sure if this alone would cause the oiling problems.

*** UPDATE *** The O-ring seals inside are rotten as well. Crack and crumble easily. Also found an orange RTV chunk in the main spin on orifice. To top it off, seems like there are two adapters in place. There is this one:

http://www.jegs.com/i/Trans-Dapt/969/1359/10002/-1?parentProductId=

as well as one of these:
http://www.jegs.com/i/JEGS+Performance+Products/555/23605/10002/-1

Am I right in assuming I need one or the other but not both???

 

[tgx]

Okay, I think I've determined the one piece is the bypass valve, although why it has a spin on adapter already on it I'm not sure, and the second piece is an adapter to use a PH30 filter. The large holes must be for the mounting bolts with 393,427 and 454 so that's not the issue. Can someone confirm this adapter arrangement is valid? I'll post a pic.

***UPDATE*** Pics in gallery 'Oil Pump Issues'

 

[cobalt327]

If your block has a flat surface around the cavity where the oil filter adapter mounts w/the two cap screws, all you need is the topmost adapter in your photos (also shown below).

But your block probably had the canister type filter originally; it takes a different set-up (like you have) in order to use a spin on filter and uses a large seal like came on the canister to seal it to the block.

So what you have will still work- but the seals need to be replaced and there's no need for silicone (if that's what I'm seeing) between the adapter and the block. If it "leaks" it still goes through the filter.

A thread w/some photos, etc.- http://www.chevytalk.org/fusionbb/showtopic.php?tid/245654/

 

[tgx]

If your block has a flat surface around the cavity where the oil filter adapter mounts w/the two cap screws, all you need is the topmost adapter in your photos (also shown below).

Yes, my block is a 67 and was of the canister variety so the cavity is dished.
I need some help in understanding the adapter so please bear with me because I believe the way it was assembled, while it 'works' I don't believe is correct. Here is the way I see it. The first adapter with bypass valve(same as the pic you posted) sits under the second adapter(shown below) which provides the mating face to the filter. The second adapters 'kit' has an inner "O" ring that the documentation claims will 'seal up against" the first adapters face. The issue is, there is 'zero way' that can occur since the size of the o-ring is much larger than the face presented by the first adapter(the so-called adapter with bypass). Without that seal there would be co-mingling of filtered/unfiltered oil which explains how the orange RTV I found ended up in the outgoing orifice in the block. Something is not right with this setup, it is almost like adapter #2 is expecting the face presented by a "non-bypass adapter" such as:

Here is the second adapter (underside shown)

 

[cobalt327]

It has been too long since I had a canister style block in my possession for me to comment on the adapter you have as being right or wrong. All I can offer is that there are correct adapters available for changing the filter style to a spin on, and there are the parts available to switch back to a canister-type filter. And there are proponents of the canister-style filters to this day. The only real downside to them IMHO is they're large and in some applications that may prevent them from being used.

 

[Richiehd]

I think I can help if I can get some pictures loaded up
First pic, the bypass adapter, this is 283, yours may be differnt
2 The filter adapter and the bypass.
3 the backside of the filter adpter showing the small round gasket(use that)
4 shows bypass installed in block (no bolts)
5 the filter adapter on top (again no bolts)
The large gasket goes under the filter adpter on the seat of the groove in the block where the old canister sealed. Throw the other gasket with the large hole and 2 small holes away. It is impossible to get all three parts lined up and the o ring in the block all at once, never mind if you are doing it on your back.

 

[tgx]

I see, so something is amiss in the setup I have.
(I also have a 283). When I disassembled the unit
I found a different bypass valve, (the one cobalt
posted) under my adapter. So apparently I am missing
the stock 1967 283 bypass valve which is needed
to make the arrangement work.

I was wondering if I could somehow modify the bypass
valve that I have by extending the center pipe using a threaded sleeve
and length of pipe such that it connects and extends through the second adapters threaded length. Probably easier to locate an OEM canister style
bypass valve.

Glad I took this thing apart though as I'm sure the oil was not being filtered.

 

[tgx]

FWIW, I have ordered the correct part from here:

https://www.paragoncorvette.com/c-23589-1963-67-oil-canister.aspx

Just posting this as a reference for future owners that might run into this issue...which seems likely given that most retailers are listing the incorrect parts for 1967 oil bypass valves.

 

[Richiehd]

Thanks for posting that link. I just saw one on Ebay and was going to post the link, and When I went to get it, it was sold, thought you might have grabbed it. That will fix your filter problems, but Im thinking you still might have pump or pickup issues. Keep us informed.

 

[tgx]

I am also replacing my pickup tube since it was a loose fit in the pump, not a 'press fit'. I'll also be checking installed height. I think the big issue that caused my problem was the large amount of excess RTV I found in the pickup strainer. Fortunately while going through the entire system I found this PRV issue which had been lurking in the shadows. Lesson learned, if you buy a second hand motor, go over the critical stuff. Fortunately I caught this before I put any real miles on the engine. My only fear now is that RTV has made it up into the oil passages.

FWIW, the oil pump is a Melling M-55 and is in good order. The nylon sleeve to secure the intermediate was cracked. I am replacing it with a Melling heavy duty intermediate with the steel sleeve.

 

[tgx]

Buttoned it back up this weekend and fired it up. Oil pressure holds steady now at 60psi, that's a 20PSI increase over previous values with no fluctuations. No oil leaks from the new spin on arrangement. The replacement adapter I received from Paragon is a very good quality repro part and fit perfectly. I used a Fel-Pro one piece oil pan seal without sealant (as per Fel-Pro) and it doesn't leak. The only problem encountered was the difficulty in rounding up the correct parts which took forever. What should have been a one day event turned into three weeks. Thanks to all who posted.

**Posted picture of RTV found in pickup strainer...moral of the story DO NOT use excess RTV!

 

[Richiehd]

Thats what this forum is for. Glad you posted your results, so many times guys don't follow up so we don't know what happened.
Dont be a stranger here.