Low oil pressure, after overheating

[J. Morgan]

What do you consider low pressure?

Does your dash gauge provide a reliable and accurate reading?

If the pressure actually is low, changing the pump probably wont help the root problem, but if I were to do this I would go high volume only, never mind the high pressure.

That said, even if your pressure is marginally low, sometimes engines with marginal oil pressure last a very long time.


Gradiens super tenui glacie.

[jonesy 1]

It is probably the spring in the pump got to hot and lost some of it temper .

[ijustlee]

I think your engine has a filter bypass spring and plunger built into the block at the filter flange. It is there to make sure that your engine gets oiled even if the filter is plugged and probably opens when the oil is cold and thick. It also regulates the oil pressure. I'd bet that a piece of crud got loose when the engine got hot and got caught in the plunger bore jamming the plunger. The engine will probably run for a very long time this way but if you want to fiddle with it I'd first check that plunger. Could there be another spot like the oil cooler bypass that got plugged with some crud? Start simple and maybe keep it that way! Waste of time and horsepower to put in a high volume pump, Chevy engineers are hard to second guess. Put 2,000 miles on oil and filter then send sample for analysis. I'd just get towing plan and not worry about it if it was me. Then again, I was told that the Aliens picked me because they liked my sense of humor!

[jonesy 1]

I meant the spring in the pump

[J. Morgan]

In a 454 the pressure relief valve is in the oil pump, the filter bypass will have no affect on pressure, and the oil cooler bypass will have no affect on pressure unless it is stuck closed and the oil gets very hot.

An oil pump is kinda like a thermostat in that when there is a problem with their respective systems this is the first thing people want to change, but changing them out seldom fixes the complaint.

If the oil pressure is indeed actually low, the problem is going to almost always be in the main, rod, or cam bearings.

HOWEVER, a kinda common cause can be sludge or debris clogging the oil pump pickup screen, but this is more common on late model vehicles that use a tiny little pickup as opposed to the large 454 pickup.


Gradiens super tenui glacie.

[Countryboy59]

Originally Posted by Grosspoluter

I've taken the RV on a few short 5 to 6 mile highway trips
oil temperature and pressure still seems to be a little high in the temperature side and Low on the pressure side
I am wondering what to expect when I pull the oil pump.
I did a oil pump on a ford FE engine and the oil pump is run by the distributor is that the way it is on this for the 454, and I'd like to ask again on any thoughts about the oil pump replacement should I use a high volume pump or a high-pressure pump? Will I need to prime the pump before or after I put it on ? If so how do I do that?
If I do get the nerve to take it home and drop the pan and replaced the pump, I will definitely get another oil analyst done

You mentioned earlier that your coolant temp is 186? That seems normal, controlled by the thermostats. You also mentioned that the initial overheat was related to a reversed fan belt, and occurred at freeway speed.

1. Did you really keep close track of the oil pressure readings before this happened? I've driven vehicles with low oil pressure (15 at idle, 40 at speed) for years without an issue. Is it possible the pressure was already low? It IS an old engine.

2. I've lost fan belts and fan clutches before, and nothing happened at speed. Didn't notice til I was idling. I wonder how bad your overheat really was?

3. The only oil analysis I ever had done was in my airplane. They are great but on most old motors there's so much crap in there that if you haven't been doing them all along it is hard to determine what changed. I have old cars (flathead and FE Fords) and I've actually had the pans down and it's the only way to really clean them out, but you'll never get everything out by just dropping the pan. The other thing that happens with old cars is people love to walk right up and argue about oil. Most have never actually been inside of an engine.

If this motor was in any of my commuting vehicles I would run it with regular oil and not worry. I know it's an RV though so the possibility of being stranded is real. I've seen guys spend hours and hours underneath, putting in high volume pumps etc etc to fix oil pressure issues only to end up with the same low pressure after they worked on it. In my younger days I ran my Torino with a blown radiator until the engine locked up. Put in a new radiator and ran it for two more years, oil light came on sometimes at low idle.

Good luck, wish I lived closer, I would go for a ride with you and listen real close to that big block. Wouldn't be surprised if you are OK. Keep us posted!

[Grosspoluter]

I did put all new gauges in the RV because I did not trust the original dashboard gauges I have video of the gauges and temperatures of when I was running it and what speeds
So I have records of the readings before and after the incident The before and after readings I'm about to list are as close to outside temperature and speed as possible before the incident On 65° day at 55 miles an hour water temperature was at 149 trans temperature was at 120 oil temperature was at 202 oil pressure was at 61 voltage was at 14.4
After the incident on a 65° day going 60 miles an hour water temperature was at 178 trans temp at 140 oil temperature at 223 oil pressure at 46 voltage 14.2
Before the incident on a 75° day going only 10 miles an hour in stop and go traffic water temperature was at 185 trans temperature at 159 oil temperature at 197 oil pressure at 46 voltage at 13.6 after the incident sitting and drive stopped on I 65° day water temperature was 200 trans temperature 166 oil temperature 214 Oil pressure 18 voltage 14.2
As for when the incident happened I don't quite recall how hot it was I know I llooked at the gauges was went into panic mode and I took my foot off the Excelerator the engine just stalled out and I cost to do a stop
As for dropping the pan and putting a new pump, I know that's a lot of work but I'm wondering about the oil relief spring / valve that people talked about on this post

[SpletKay06]

Personally as a guy with an associates degree in auto/diesel industrial your after numbers are far better than your before numbers. Quit worrying and enjoy it!

[Naper]

I would question the before temp of 149, its too low for proper combustion. Big block Chevys will run 180 - 200.
As others have said low oil pressure is usually a main bearing problem. Do you have a knocking sound on cold start up?

[Grosspoluter]

So I got the OK from my storage place to work on the RV while it's sitting in the spot
My first question is has anyone pull the oil pan off one of these?
It looks pretty simple but I'm wondering about getting it out from underneath, is the crossmember in the way?
Is there anything I should know about?
also putting it back on is there any tips or tricks?
I've ordered a high volume oil pump, and a new oil pump shaft.
I won't know until I get it out, but I've seen some people say they don't use a gasket between the oil pump and the engine, they claim the machine surface is good enough, is this true?
I plan to prime the pump before I put it in, but do I have to prime the motor with the pump? I'm not removing the motor, so all the residual oil will still be in it...
I ordered, and received two oil pan gasket's just in case I mess up the first one😖
Any thoughts or ideas would be much appreciated
(I've got the front end up on some 4 x 4 wood blocks with wheel chocks of course)

[mehes]

I messed with mine a few years ago. Ask recall I took the bolts out of the motor mounts and jacked the engine as high as I could get it without hitting anything and blocking it there. I then tried to remove the pan but could never get it off because of the cross member. I did remove and replace the oil pump with the pan wedged in there. Kind of like building a ship In a bottle, blindfolded, around a corner with boxing gloves on. I can't remember what prevented the engine from going higher. Take a good look what it might hit. It might be worth your while making every attempt to get it higher. I still have cuts on my wrists and arms from this job. Good luck.


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[Isuzusweet]

Originally Posted by mehes

I messed with mine a few years ago. Ask recall I took the bolts out of the motor mounts and jacked the engine as high as I could get it without hitting anything and blocking it there. I then tried to remove the pan but could never get it off because of the cross member. I did remove and replace the oil pump with the pan wedged in there. Kind of like building a ship In a bottle, blindfolded, around a corner with boxing gloves on. I can't remember what prevented the engine from going higher. Take a good look what it might hit. It might be worth your while making every attempt to get it higher. I still have cuts on my wrists and arms from this job. Good luck.


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Yup! One of those "give it to Mikey; Mikey will do it" jobs; also known as the "did it once; never again" jobs.

I sometimes prefer to spend money to save my sanity and my flesh.

Goodluck, but be honest with yourself and your expertise BEFORE you undo the first bolt; the first bolt is always the easiest, not so the last bolt. Remember, Mehes is an engineer!!!

Cheers
Tony

[Grosspoluter]

I understand the complexity of it, and I did oil pump on a car once.
As I remember correctly, I had to turn the engine a quarter of a turn, or a full turn or something like that, to get the counterweights from the crankshaft out of the way to pull the pan out... oh, and I already have drained the oil and I have 5 of the pan bolts off... Am I confident🤔, maybe... Am I scared HELL YEAH!!! 😳
"as I jump off the diving board, I suspect that the pool will be filled by the time I get down there"😅

[Grosspoluter]

Unfortunately for me the motorhome and 76 miles from my home.
Also after doing some research on another thread in this form and a couple another forums, I'm starting to worry. People are talking about they had to jack the engine up, slide the transmission back just to get the pan out.
It'll be a while before I can go back and take a look at it, but I'm wondering should you jack up the transmission end? I mean the deep part of the pan is hitting the transmission. If the transmissions front was tilted down (by lifting the transmission rear, up would the pan then slide out?
Not sure how to tag the thread here but it was called something like between a rock and a hard place and had an excellent picture

[Grosspoluter]

The thread was posted on 5-15 -2008 it was titled between a rock and a hard place 454 p-30 chassis chassis
poster was schaapveld4

[Smartstream]

From the looks of the picture you will have to move the trans back several inches and remove the flex plate. If you are in to it that far I would recommend looking at the bearings. They are accessible with the pan off and new bearings are a great way to pump up the oil pressure.

[ijustlee]

Is that photo of your motor home or from the article? I once worked on a 454 pickup for a lady who towed a heavy 5th wheel out to California from the east coast of Canada and wanted me to check it out for the return trip. The oil pressure indicated by factory gauge was low, as I recall 15 at idle and 40 at high RPM and changed with the engine speed. The owner didn't know if it had always been that way but thought so. Changed oil & filter and it didn't help the oil pressure, I thought that the relief valve was stuck open or there was a flaw in the engine casting. The owner had bought the truck new and always took real good care of it, had towing insurance, so I recommended she drive it home with the trailer and buy tires and get some brake work just before crossing back to Canada. She took off on a round about trip home that included a couple of trips back and forth across the Rockies. 20 years later she was back here and told me that the trip went well and the truck was still running great! Based on that I don't think that you have a problem. At most a stuck relief valve or dirty pick-up screen, but still enough oil pressure to do what needs to be done. Sure want to hear how this works out though.

[Grosspoluter]

Photo was taken from a previous poster
Not sure if I want to do all the work of moving the transmission back and lifting the engine up
I certainly don't want to do it at the storage place.
today I put the pan bolts that I originally took off back in and put oil back and started it up.
I'm thinking about taking it home and working on it.
I just need enough nerve to make the 70 mile trip. DEFIANTLY will have my wife follow me in a chase car, who knows maybe once the first 70 miles under my belt I'll feel better about it and not want to take the bottom end the apart😏

[jake74]

My old allegro had a 454 and it always idled on 20 and 40 down the road. Ran the dog out of that thing pulling a 16 foot enclosed loaded with quads and dirt bikes. Think your worrying a little to much.

[Grosspoluter]

Super nice day in northern Illinois today
Wife Amy and I took the 345 for a short highway run and to Rock Cut State Park today
I really liked the numbers I got this time,
60*F outside temp, 65 mph, 2900 rpm's, coolant 191*, trans 128*, OIL 225*, OIL Pres 52 psi, voltage 14.1 and fuel 4 psi (with the help of a rear electric fuel pump)
Next nice day I think I'll take the 70 mile trip home!
Not sure why the oil temp and pressure got better, maybe it's just all the flushing it's got in the last 4 months... 100 miles, maybe 10 hours and at least 5 full oil changes with filters
Maybe I should stop being such a worry wart[emoji57]



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