low oil pressure

[Racer X]

On 2/1/2023 at 11:03 AM, Wally said:

 

No sir, i dont think it ever was right. I was thinking, at first, the gauge just wasnt working so it wasnt really registering much of anything for oil pressure. I swapped gauges out and it still wasnt doing anything but the temp gauge was working. Thats when i figured something else was wrong. i tried a couple diff. mechanical gauges. Idling around 1000rpm pressure was in low teens..i believe 12-13, but when i revved engine up pressure oddly went down to maybe 11.

Well, again, this is something that should have been addressed immediately with the builder, before trying to suss it out on your own, especially given your lack of mechanical experience and knowledge, but what has been done cannot be undone, so the best we can do is move forward.

So far you have an idea of what the rod bearing clearances are. Nothing jumps out there.

Next up you should check the main bearing clearances, and post the results here.

On reassembly of the oil pickup and pan, I suggest you use thread locker on the oil pickup bolts, and a very thin film of silicone sealer on both sides of the gasket. 
 

It looked like the pan rail was pretty clean, and if you recall I did ask if the builder used any sealer. If no sealer was used on the oil pan gasket, and the correct gasket (I’m talking the master the gasket is made from, the OEM, and the OEM quality aftermarket gaskets) was used, it can be reused multiple times, providing it isn’t damaged.

Once you have the bottom end buttoned up, refill the crankcase and install a new filter.

 

You obliquely mentioned that you had removed the oil pump, and I’m still not clear if you replaced the pump with new during the rebuild, or if you reused the old one.

Did you disassemble it and check it according to the factory service manual? As I mentioned, the process is detailed in the manual, and is easy to do. You clean and inspect the gerotor (that’s what the two metal pieces are called that actually move the oil), then place the parts inside the housing and use a feeler gauge to check the clearances. If it is determined that 5he pump is serviceable, lubricate it and reassemble.

Also check the pump pressure relief spring. I’ve already shown you where it is.

I suspect there may be a problem either with the oil pump, it may be worn beyond limits, or with the pressure relief spring, it may be broken, or has lost tension, or is simple too weak.

 

After that, if you still don’t have good oil pressure, you really need to have a conversation with the builder.

 

And don’t spend a lot of time running the engine until you are certain that it has proper lubrication.

 

[Racer X]

A comment on the use of Plastigauge.

As I mentioned, do not rotate the crank while performing this task, the plastic will get smeared and result in an erroneous reading.

Additionally, lay the bit of Plastigauge directly in line with the crankshaft, not at an oblique angle. I find using a tweezers helps with precise placement here.

 

 

[Wally]

4 hours ago, Yarb said:

Did you install the gauge directly into the block with the brass fitting adapter? If not I’m not confident with any of the previous attempts. I’ll post a pic of how mine is configured.

i did connect directly to the block using the brass fitting. It was nice and snug

[Wally]

4 hours ago, Zed Head said:

If it was mine and I was unsure I probably would have tapped a hole in to an oil filter and stuck my gauge there, just to verify what the gauge port showed.  The filter is full of very slow moving oil.

interesting. never heard of that before

[Racer X]

4 hours ago, Zed Head said:

If it was mine and I was unsure I probably would have tapped a hole in to an oil filter and stuck my gauge there, just to verify what the gauge port showed.  

How would you tap a tapered pipe thread in a sheet metal can a few thousandths of an inch thick?

[Wally]

3 hours ago, Racer X said:

Next up you should check the main bearing clearances, and post the results here.

OK. i think i can do that. i looked at the service manual. i think page 21/22. It said clearance between .0008 to .0028 and main bolts torque to 33-40ftlbs. Unless someone knows different this is what i will go with.

 

3 hours ago, Racer X said:

On reassembly of the oil pickup and pan, I suggest you use thread locker on the oil pickup bolts, and a very thin film of silicone sealer on both sides of the gasket. 
 

Yep. already did. I did that before i knew i was doing this clearance testing. Can still get to everything though.

3 hours ago, Racer X said:

It looked like the pan rail was pretty clean, and if you recall I did ask if the builder used any sealer. If no sealer was used on the oil pan gasket, and the correct gasket (I’m talking the master the gasket is made from, the OEM, and the OEM quality aftermarket gaskets) was used, it can be reused multiple times, providing it isn’t damaged.

Yes its real clean no sealant was used. I did check it for leaks a month or so ago before i started this process. I do have another new OEM gasket gonna use

 

3 hours ago, Racer X said:

You obliquely mentioned that you had removed the oil pump, and I’m still not clear if you replaced the pump with new during the rebuild, or if you reused the old one.

The oil pump that was on it before i just took it off was almost new, but you never know. Heck i went through 3 new alternators before i got one that worked. I have another OEM pump, that is already on. I checked it all over and it looks good...at least to me.

 

[Zed Head]

3 hours ago, Racer X said:

How would you tap a tapered pipe thread in a sheet metal can a few thousandths of an inch thick?

There's always a way to not get things done.  It was a concept idea.  You could poke around in the port hole too.  Ponder why the gauge needle would move so rapidly when it's just sitting there on the small channel to the oil filter, which is like a big buffer pool of oil.

Anyway, just offering ideas about what I would do.

I really hate how Google or eBay or whoever adds so much extra crap to eBay and Amazon links.  Probably contains all of my recent browsing history, in code.

Here's a picture instead.

[Racer X]

6 hours ago, Wally said:I do have another new OEM gasket gonna use

 

 

As I mentioned, if the gasket that was on it is not damaged, and is the correct type, it can be reused.

[Wally]

ok. got the main bearings  off. All fell within parameters around .0015 inch. 

I did test the torqued amount of the bolts, 50ftlb...WOW. Service manual says upper limit of 40 so these like connecting rods are way overtight. Redid them all to around 38.

tomorrow will put oil pan back on

Edited February 3, 2023 by Wally

[Captain Obvious]

I'm not a mechanical engineer, but I have serious reservations about using the torque required to crack a bolt loose to determine what said bolt was originally torqued to. I mean... I bet it's proportional (like the more it was torqued to, the more it would take to break it free), but as far as determining absolute value... I'm very skeptical.

@Wally, You just torqued your main bolts to 38 ft-lb, right? Put your wrench back onto a couple of them and see what torque it takes to remove them. See if it takes 38, or if it takes more than that. I bet it takes more.   

Static friction is higher than sliding friction and all that?

[Namerow]

Fastener torques.  A great topic for deep reading.  Here's a starting point:

Lubrication Effects on Fastener Torque Specs - EngineeringToolbox.com

Lots of interesting links at the end of the article.

Another good source of information is the late Carroll Smith's book, 'Nuts, Bolts, Fasteners and Plumbing Handbook'.  Smith was manager of the Shelby American race team back in the day and specialized in bridging the gap between engineering theory and real-world motorsports reality.  It's an old book, but I don't think too much has changed.

[Wally]

12 hours ago, Captain Obvious said:

 have serious reservations about using the torque required to crack a bolt loose to determine what said bolt was originally torqued to. I mean... I bet it's proportional (like the more it was torqued to, the more it would take to break it free), but as far as determining absolute value... I'm very skeptical.

Not what i did. Here is what i did. I put my torque on something low like 20. i tried to tighten the bolt. It clicks. so i move it to 21, click and so on until it doesnt click anymore but begins to tighten a little. I know that is odd way to do it but that is what i did