My '85 MGM, "Maisa"

[87gtVIC]

This sucks.


I too had an unfavorable "first start" when I did my engine rebuild.

My issue wound up being a severely warped flange on the tubular intake manifold causing a massive vacuum leak which sounded like a supercharger.

The same build was followed up by two head bolts breaking and dumping coolant out on me. One required a 300+ dollar tow while the other happened in the backyard! Yes, they did not happen at the same time. Needless to say all head bolts were changed out with supposedly better hardware when the heads came off and the offending bolt was extracted.

I feel your pain. Good luck.

[Tiggie]

I ran 20w50 in an extremely well worn 390 and the lifters sounded like heck on cold start up. Switched back to 10w-40 and the problem fixed itself.

[sly]

It's a sound theory (*rimshot*) for sure. No clue how to test the theory or how to verify any of that, unfortunately.

[friskyfrankie]

I ran 20w50 in an extremely well worn 390 and the lifters sounded like heck on cold start up. Switched back to 10w-40 and the problem fixed itself.

I've already mentioned my issue with heavy oil to try and fix an issue. Especially if it might be causing one. I do, however, understand his logic for using it.

[Arquemann]

I ran 20w50 in an extremely well worn 390 and the lifters sounded like heck on cold start up. Switched back to 10w-40 and the problem fixed itself.

I've already mentioned my issue with heavy oil to try and fix an issue. Especially if it might be causing one. I do, however, understand his logic for using it.

The main issue here is the rattle when running, the most obvious difference between running 10W30 and 20W50 is that the latter kept the rattle quiet for longer upon startup, where the former rattled just as loud at start. Sure it'd just be another 30-40€ for a jug of oil, but I am still unemployed on pisspoor welfare and I've already wasted one jug. I don't quite feel like pouring another one in just so one noise turns into another one like it was earlier, just because.
I don't have any oil pressure problems as I have a new oil pump and factory fresh tolerances, so I don't really understand why the viscosity difference would cause the clatter on cold start. If the lifters are draining back like I've theorized, it wouldn't matter which oil is in it. It's got 55 psi of oil pressure on a warm engine, surely that's not excessive?

[kishy]

The thing to look out for with oil pressure is that it doesn't tell you the whole story.

The pump is pushing oil into what is fundamentally a tube with many holes. All of those holes need a certain amount of flow through them.
The pump pushes the oil hard enough to create pressure. The pressure against the holes creates flow.

Low oil pressure would be seen when some of the holes - let's say main bearings or whatever - have gotten too big and the oil escapes the holes faster than the pump can keep pressurizing the pipe.
You put a thicker oil in, now the oil resists flowing through the holes as easily, which keeps the pressure up because now the oil is escaping more slowly through the widened holes.
But what about the holes that aren't widened (which in your case is potentially all of them)? Is the thicker oil flowing through them enough to lubricate things now?

The part of the equation that's easy to overlook is the oil pump relief/bypass, which I'm fairly sure opens in the mid 50s, so if your gauge shows 55, it's fundamentally "pegged" and bypassing because the oil isn't escaping the holes fast enough. Or that's my understanding anyway. The confirming clue for me that a 40 weight (5W40 in my case) was a reasonable choice is that my pressure doesn't sit at 50-anything for very long before it starts calming down.

I have no idea if 20W50 is thick enough to create a problem here. If anything I'd expect it to cause a little bit of noise on a cold start and then shut up after a few seconds, because it's initially a little harder to get it moving, but once it's moving and warming up it's fine. The pattern of a noise developing after that is not one that I really can wrap my head around.

[sly]

Yeah... makes me think he may be correct about the lifters being junk out of the box.

[matth825]

I think the theory about the lifters being junk is sound especially with them being the Enginetech brand from RockAuto. I’d look into a set from Ford Performance. One would hope those are made to a higher standard.

[Arquemann]

The thing to look out for with oil pressure is that it doesn't tell you the whole story.

The pump is pushing oil into what is fundamentally a tube with many holes. All of those holes need a certain amount of flow through them.
The pump pushes the oil hard enough to create pressure. The pressure against the holes creates flow.

Low oil pressure would be seen when some of the holes - let's say main bearings or whatever - have gotten too big and the oil escapes the holes faster than the pump can keep pressurizing the pipe.
You put a thicker oil in, now the oil resists flowing through the holes as easily, which keeps the pressure up because now the oil is escaping more slowly through the widened holes.
But what about the holes that aren't widened (which in your case is potentially all of them)? Is the thicker oil flowing through them enough to lubricate things now?

The part of the equation that's easy to overlook is the oil pump relief/bypass, which I'm fairly sure opens in the mid 50s, so if your gauge shows 55, it's fundamentally "pegged" and bypassing because the oil isn't escaping the holes fast enough. Or that's my understanding anyway. The confirming clue for me that a 40 weight (5W40 in my case) was a reasonable choice is that my pressure doesn't sit at 50-anything for very long before it starts calming down.

I have no idea if 20W50 is thick enough to create a problem here. If anything I'd expect it to cause a little bit of noise on a cold start and then shut up after a few seconds, because it's initially a little harder to get it moving, but once it's moving and warming up it's fine. The pattern of a noise developing after that is not one that I really can wrap my head around.

I'd like to consider myself somewhat knowledgeable in basic fluid dynamics. The 20W50 was put in as an experiment to see if it changes anything, and it seems to have done so, for better or worse. Wasn't intending to run 20W50 all the time.

Thanks for info on the oil pump bypass, I've kinda understood old V8 oil pressure "is what it is", and tbh wasn't exactly sure a SBF had an internal pressure bypass. Knowing this I do think the 20W50 is too thick if it is keeping the bypass open all the time. I was wondering why the cold and hot oil pressure readings were so close to eachother.

Nothing in the engine assembly is amiss, I have oil pressure and flow everywhere that needs it. The only complicated parts in a SBF are the hydraulic lifters.


Currently the cheapest way for me to acquire new roller lifters (excluding cheapo EngineTech, Ultra-Power and whatever QualCast is) is to go and locally buy a set of FRPP lifters. 188€ for a set, so not a purchase I'd like to do willy-nilly. Ought to be quality pieces. Convenient though, as I could dismantle and inspect, and not have to wait a week for new bits.

[gadget73]

isn't the relief valve built into the oil pump ? I know its got one in the system somewhere but I've never actually fooled with it. Most likely just a simple spring and check ball sort of thing though, and 50-60 psi for the relief sounds about right.

[Arquemann]

Yesterday I dug through dad's oil cabinet, which happened to have a bottle of Liqui Moly lifter additive, so I dumped it in for kicks. It's supposed to reduce lifter ticks and clean up if any gunk or debris that might've gotten stuck in the lifters. It's pretty thin stuff so it won't hurt anything.

I eyeballed the TV cable a bit on the tight side, made sure it wasn't bottoming out on WOT, and went for a short shakedown run and some fresh fuel. Adjusted it a bit looser, but still shifts a bit too firm and late, but atleast it's driveable now.
Put a couple more miles on it, still sounds like shit and idles rough. Now that the accelerator pump works like it should, it goes lean when I stab the throttle while driving. Now I'm not sure if have to get a larger pump jet to get more fuel faster, or a smaller jet so the pump shot would last longer.

The inspection ran out a couple weeks ago, so I can't really drive much. I'm just wondering if I should try and get it inspected again before tearing it apart to possibly change the lifters. If it's indeed junk lifters and the valves are opening less than normal, it might affect the emissions negatively too. Running rough doesn't help either, whatever is causing that.

[Arquemann]

Inspection date set for next thursday, hope it'll pass so I can get a breather and some more flexibility in testing the waters regarding the engine's health.

Tried gooping and gasketing the cat flanges one more time, if they blow out, I'm chopping them off. Inspectors really like exhaust leaks, because it's an advisory plus screwing up emissions checks due to extra oxygen coming in.
I've noticed a leak from the front drain plug, prolly needs a new crush washer, dunno how much oil I'd lose as the car is on ramps up front.

Been chatting in our Ford club group chat about the engine rattle, not many seem to be buying the idea of junk lifters all the while the old farts keep complaining about all new parts being junk. Most give suggestions about lifter preload, oil pressure, piston slap, bottom end bearings and such. Someone said internal oil leak, sure I don't have a way to check that, but I feel like it'd be unlikely for me to have missed a galley plug and still have 55psi hot.

If I don't happen to find enlightenment regarding the rattle in the near future, I'll probably spring for new lifters.
Sucks extra because for once the intake ends aren't leaking, despite my reservations towards the rubber end gaskets.

[jaywish]

Have you posted a sound file, that I missed?

[Arquemann]

Have you posted a sound file, that I missed?

A video link in post #1368 on page 92. Also there's a couple sound clip links somewhere earlier in the thread.

[jaywish]

You have tried the long metal object or a auto stethoscope to isolate this?