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js65cobra
10-13-2020, 04:02 PM
Hello,

So let me start by saying, I am fairly confident the answer is going to be pull the pan, check the bearings. But I wanted to outline my story and see what you guys think.

Ok, so to start, I purchased my FFR from my father about a year ago. He was the second owner of the car of which he purchased it back in 2003. In the time from 2003 to 2020 he put 1300 miles on it. (He has a bunch of other classic cars so this one did not get driven much) Hence why I purchased it from him and in that time of a year have put about a 1000 miles on it.

The engine is a 302 from a 93 mustang gt. It was bored over .030 to end up at 306ci. It has speed pro pistons and the crankshaft was turned 10-10. It has an F303 cam installed and the heads were shaved and ported when built, it also had Ford Racing valve springs and an Edelbrock air-gap performer intake installed. << That was all the info we received from the original builder of the car back in 2003.

Anyway, when I got it, I noticed the driver side cylinder head had a bolt that was sheered off. The head of the bolt was missing and could see rust marks and water marks on the firewall. So around thanksgiving last year we decided to take the head off and put all new bolts on that head. So we took off intake, headers and the head and were able to get the bolt out pretty easily (hindsight should have tried to just extract the bolt with the head on, it was that easy to remove). We got the new head gasket, and bolts put back on after doing a cleaning of the head surfaces.

Now, is where we failed. In our rush to put things back together, we borked the intake installation. When we installed it, there was a gap left on the intake on the water ports and thus when we started it up, it ended up with coolant in the oil. We shutoff the engine pretty quickly (maybe a minute), and realized that we had coolant in the oil. After some discussion we figured it must be coming from the intake, and then reinstalled it again, but this time I don't believe we gave the RTV sealant long enough to set, and thus ended up with coolant once again in the oil....So next, I figured out my problem. I was using the felpro gaskets and I should have used just RTV on the valley seal instead of those silly rubber gaskets. lesson learned. So this time, I dumped a bunch of oil down to flush out any coolant from the topside, and I also dropped the pan and cleaned out any coolant left in the pan itself. Installed the oil pan, and installed intake properly this time. And finally on startup, no oil in the coolant! This was around December last year, and thus living in Colorado, didn't have much time to run the car and see how it worked outside of just starting it in the garage. I only drove it maybe 50 miles or so, but I did notice the oil pressure gauge started at 40 psi around cold startup, but then would drop to around 10psi once warm at idle.

As an aside, around January I decided to install a holley sniper system as well, and thus spent a bunch of time tuning and getting that going. I kept noticing the oil pressure was low, but I never really remembered what it was before we did all that work, so honestly pushed it aside since the car makes 0 noises and sounds great. It runs and drives as expected and I don't hear any knocking or valve train issues.

But my concern is could I be hurting the engine, or did my oil pressure gauge just go bad? Its a smiths gauge with a poly line to the gauge. I suspected perhaps some coolant may have gotten into that gauge and caused it to not read as well as it used to... I thought about getting a new gauge (but alas here I am asking if I should).

When cruising at about 3000 RPM it shows around 20-22 psi on the gauge. If i let off the gas and let it coast while in gear, the pressure goes up (I have read this could indicate bad bearings). It never goes above 30 psi on the gauge when its warmed up.

So... my questions are:

1. What should I be expecting for oil pressure? Surely not that low at hot idle right? (sometimes even as low as 5psi on the gauge). I've seen 10 psi for every 1000 rpm, and my idle is set to 900, and i get about 9 psi at idle...
2. Are my bearings shot?
3. Should I try a heavier oil? I run 10w-30 now.
4. Should I get a new gauge and test that?


Sorry for the long post, but I wanted to be sure to include all the details as I have them, thanks for checking it out.

Egodro
10-13-2020, 05:16 PM
First thing to do is to put another mechanical gauge to figure out the real oil pressure....

TrevorP
10-13-2020, 06:11 PM
usually below 10psi hot idle, the bearings are worn. That is when I knew it was time for a rebuild - if the engine made it that far without something else letting go.

15-20 hot is more typical. 40-45 at revs with a standard oil pump.

js65cobra
10-14-2020, 08:16 AM
Thanks guys, I am going to see if the gauge is bad with a new mechanical one and then go from there.

Al_C
10-14-2020, 09:10 AM
I also think agree mechanical gauge is a good place to start. I'd also check your bearings. It sounds like the crank was out of the engine when the mods were done, but we don't know how much wear there was/is on the bearings or if they were swapped out at the time.

I had a similar situation on a German Ford 2.8 V6. Couldn't maintain pressure and heavier oil didn't help. It was the bearings.

edwardb
10-14-2020, 10:11 AM
Agree with other comments that you need to confirm with a mechanical gauge. If confirmed, those readings are definitely on the low side. You could try some heavier weight oil (all the major brands have versions for "high mileage") and maybe buy some time. It could go a long time just the way it is. Or not. Had a similar situation with my first build. Bought what was supposed to be a good engine. But wouldn't hold decent oil pressure no matter what I did. Pulled the bottom end out and found this. Pretty heavy wear and didn't do the crankshaft any favors either. Hopefully yours isn't this bad.

https://hosting.photobucket.com/albums/ab234/edwardb123/Factory%20Five%20Mark%203%20Roadster%20Build/Engine%20Overhaul/.highres/IMG_1289.jpg (https://app.photobucket.com/u/edwardb123/a/ab1fc29e-cb74-48d0-9f11-e79be8968f75/p/55799e5c-a030-4bfc-afeb-6956188191eb)

JohnK
10-14-2020, 12:16 PM
FWIW - I have a '67 Mustang with a 351W that had oil pressure problems. At hot idle pressure would drop to almost zero and the idiot light on the dash would flicker. I tried heavier weight oil and that didn't help a whole lot. I wanted to get a little more life out of the engine, and was planning to replace it entirely eventually so I figured I didn't have much to lose by just band-aiding it for a bit. I put a high volume oil pump in it, and it made a decent difference. Pressure at hot idle is now 10-15 PSI and while driving it's in the 30-50 range. I'm totally happy with that for now, as it probably bought me enough time on that engine that I don't have to deal with replacing it until I'm done with the roadster.

js65cobra
10-14-2020, 12:59 PM
Thanks guys, yeah I'm really hoping the gauge is just bad, but we shall see. I now wish I paid more attention to the oil pressure before we did everything to know if it was always this way or happened as a result of the coolant issues. I will let you know what I find out when I get the new gauge.

NAZ
10-14-2020, 01:22 PM
Here's hoping that you just have a bad oil pressure reading and that a mechanical gauge will confirm good pressure.

However, if you take JohnK's advice, while you're in there pull at least one main cap to inspect it. If it looks anything like the photos above -- the bearings are done. And if you decide to try extending the MTTR at least you will know how bad the damage is and potentially how much time you might be able to buy. But this is a desperate measure, not a fix. And if this was damage from coolant mixed with oil, expect the rod bearings to look the same. At minimum, cam, lifter, wrist pins -- all need to be inspected for wear as these are subjected to high loads so don't cheap-out and just replace bearings and have the crank ground as other wear items may be beyond their wear limits as well. If you pull the pistons you will want to replace the rings. Engine overhaul will be a series of one thing leads to another.

Good luck.

JohnK
10-14-2020, 01:37 PM
I agree 100% with NAZ that my approach was, if not a desperate measure, at least a path from which there is no return. If I had any notion of wanting to rebuild this engine I would not have gone down this path. The longer I run it this way, the more new problems I'm layering on top of existing problems, as NAZ points out. However, my long-term plans for this car don't involve rebuilding this engine, so I don't have much to lose from running it until it dies.

js65cobra
10-20-2020, 02:32 PM
I was able to get another mechanical gauge. It showed 30 psi on startup, which is basically the same as the other gauge, so it seems the pressure may be bad, and looks like I need to investigate bearings and such.