Low oil pressure, after overheating

[Kota]

Originally Posted by J. Morgan

True, I have taken several engines apart, the ones that have been very hot have a distinct smell of burnt oil.

Even then though, the bearings were not compromised.

It takes a pretty long heat sink to compromise the bottom end, and in most every case a person would have developed a top end failure in concert. (Blown head gasket, cracked head, scored or melted piston)

What makes me think something else is up is that this engine seems to have suffered bottom end damage and apparently no top end damage, this is not what I would consider normal for an overheat.


Superat stultitia.

Might be low oil pressure caused the overheat. Since it was verified by gauge that oil pressure is low, and it's not a filter issue, the pan will have to be pulled to replace the pump. I'd check out the bottom end too. A compression check might reveal some top end damage.

[Grosspoluter]

Does the 454 have a by pass valve? I don't know?
My engine does have a external cooler.
Anyone here ever have trouble with one? or ever replace one?

[joel]

If previous owner used 5/30 he was unbelievably lucky or did not use the rig in any kind of hard heavy driving. I have worked on my motors for years and 10/30 at least . I would run 10\40 And replace 2 quarts with Lucas oil and a napa gold filter . You can get a pressure test kit and put it on to test the accuracy of your electronic gauge. If you over heated you could have very easily clogged or damaged your oil pressure sensor. Running 5\30 is like pumping water thru thru a 454. Running hot can also gunk up the oil pump. The easiest way to check for sludge build up in a motor that can happen over time is to pull a valve cover and look for build up around rocker arms and drain holes on heads. Good luck.

[Boom Sounds]

10w 30 mineral all day long. I see no point in going synthetic or 10w 40. I would suggest you take it into a reputable truck shop and get them to run some compression tests and take it from there.


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[J. Morgan]

In a motor with compromised bearing clearances to the point of causing low oil pressure, 20/40 is what I would run. To each his own though.

A compression check really has nothing to do with a compromised bottom end or cam bearings.

As far as 5W oil, I wont use that grade on anything, particularly an older engine. For me that goes for 10W too. (There is no way I would run these in a flat tappet engine, the zinc-less oil sold today is catastrophic enough for non roller cams)

These grades are more about vehicle manufacturers making CAFE standards than they are about engine protection.


Superat stultitia.

[J. Morgan]

FWIW, while the oil pressures you are running now are marginally low for a 454, in absence of other problems I would not jump into a rebuild, with thicker oil, the engine could still last for a very long time.


Superat stultitia.

[Grosspoluter]

I would never use 10/40 I consider it garbage
I used to use it on my first cars way back (1980)
But when I restored my 1967 ford countrysedan with a 390 in it you could watch the 10/40 get hot and oil pressure would suffer a friend of a friend who race cars at the Rockford speedway told me not to use the 10/40 and use 10/30
There was a noticeable difference when things got warm on the 90* summer days oil pressure did not suffer nearly as much
In leaning to 10/30 from now on! In my motorhome

[NevadaGeo]

Wondering, what about Slick 50 or a type of teflon stuff? I had a Dodge Omni with Slick 50 in that I lost the fan belt going to work once, I went over Kingsbury grade to work twice before it occurred to me that I also had lost the water pump.... engine was way hot, but just used more oil after that. I always credited the Slick 50 for the engine to still be running.

[J. Morgan]

"Thinner oils improve fuel economy. But if the oil is too thin, it may not provide enough film strength at high temperature to protect the bearings in an engine with increased bearing clearances. On the other hand, thicker oil is good for maintaining good oil pressure in a performance engine. But if the oil is too heavy it may interfere with the normal operation of the variable valve timing system, or be slow to circulate when a cold engine is first started. Churning excessively thick oil can also generate heat and rob the engine of power."

http://www.enginebuildermag.com/2014...ing-right-oil/


Superat stultitia.

[Boom Sounds]

Check out the Chevytalk.org forum. Guys on there like Chevytech will give you a definitive position on your problem.

[Grosspoluter]

I'm going out to the motorhome this week, probably early Friday morning
I'm hoping to do another filter and oil change.
I know I'm opening a can of worms here and I've seen the oil threads on this forum but any advice received will be filtered through my thick skull and I'll make a decision.
Right now I'm leaning to go to, and stick with a Mobil oil, I'm thinking a 10/30 or maybe a strait 30w oil probably non-synthetic
I'm hoping to get enough nerve to take it out for a test drive
Any advice given for the test drive, again will be filtered through the same thick skull😏
"Kota" mentioned that maybe the low oil pressure caused the heat but I KNOW this is not true because I saw the missing fan belts (I'll do my best to check belt alignment when I'm at the motorhome)
The motorhome is at a self storage place about 70 miles from home so I can't Do any major work like pull a pan without first driving it home and I live in Illinois where road construction is horrible!
As for the burnt oil leaving a "varnish" I'm hoping a few more, more frequent oil and filter changes will help with that?
I'm now scared to even take it out for the test drive!
Ya know how it is once a vehical leaves ya stranded, you never really trust it any more!
So if at 11am central time on Friday everybody could cross their fingers for me...
I'll leave a few more updates, maybe I'll even go out this evening and give it a try

[Waipio Rim]

This fall we plan to fly in to Salt Lake, pick up the 310 at a shop where it is getting some work done, and start driving toward San Antonio with absolutely no idea of what our oil pressure numbers are. As long as it's running cool and quiet and the needles on the dash gauges are pointing generally straight up, we will just keep going.

[crispyboy]

If I were in your shoes I would get an oil analysis done as mentioned in a previous post. I would also be running a zinc additive or 15w/40 diesel oil which still contains some zinc. I have used 15w/40 oil in older gas engines with no problems - more consistent oil pressure readings.

[Kota]

Originally Posted by Grosspoluter

I'm going out to the motorhome this week, probably early Friday morning

I'm hoping to do another filter and oil change.

I know I'm opening a can of worms here and I've seen the oil threads on this forum but any advice received will be filtered through my thick skull and I'll make a decision.

Right now I'm leaning to go to, and stick with a Mobil oil, I'm thinking a 10/30 or maybe a strait 30w oil probably non-synthetic

I'm hoping to get enough nerve to take it out for a test drive

Any advice given for the test drive, again will be filtered through the same thick skull😏

"Kota" mentioned that maybe the low oil pressure caused the heat but I KNOW this is not true because I saw the missing fan belts (I'll do my best to check belt alignment when I'm at the motorhome)

The motorhome is at a self storage place about 70 miles from home so I can't Do any major work like pull a pan without first driving it home and I live in Illinois where road construction is horrible!

As for the burnt oil leaving a "varnish" I'm hoping a few more, more frequent oil and filter changes will help with that?

I'm now scared to even take it out for the test drive!

Ya know how it is once a vehical leaves ya stranded, you never really trust it any more!

So if at 11am central time on Friday everybody could cross their fingers for me...

I'll leave a few more updates, maybe I'll even go out this evening and give it a try

The worst part about it is not having the confidence to take it out on an extended road trip. You can get a reman or crate engine for about the cost of a good tow. Finding a decent shop to install it for reasonable might be a challenge.

[overlander63]

I've had a couple of high mileage engines suffer low oil pressure after an overheat event. One had a partially clogged screen on the oil pump pickup, the other had a bypass spring partly collapse. The clog was from the sludge in the engine loosening from the high temps, and getting sucked into the screen. The filter bypass spring issue also seemed to be from sludge getting in the way.

[jonesy 1]

There is a valve in the pump with plastic parts ,the pan is not hard to remove lower pan as much as you can then drop the pump in to the pan the pan will now slide out easily. I would replace pump if necessary stock pressure high volume..and Lucus is great stuff.

[tjdonahoe]

With a good oil you need no additives, my cat has 1.4 million miles , no additives, none nada.....

[Grosspoluter]

Ok so I went out this evening and did yet another oil and filter change after running the engine for about an hour
During that hour I let it get to normal operating temp 210*f
I think it was on another forum I read something about if it was a main bearing being bad it would loose oil pressure under load so I took these readings
210*f 1500rpms in park 35psi
210*f 1500rpms in drive (with breaks applied - basically a "break torque") 30psi
Ya I know the break torque is hard on... Everything but only took 5 seconds to get the reading😏
Took it for a very short ride around the storage facility's parking lot, didn't go over 15 mph but never got over 30 psi
I just didn't have the courage to take it out on the road😒
I did take "Kota's" advice and ordered the oil analysis kit and collected a quart sample to send in when the kit gets to me
I refilled the engine with non - synthetic 10/30 and put another new filter in

[Boom Sounds]

Good stuff, is it worth running it with some sea foam or other engine cleaner, then, after you have been brave enough to take her for a spin and got a few miles on her, do another full oil change with the 10/30 mineral. You've probably got a heap of burned crud in there.



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[Grosspoluter]

Ok yet another update
Went to the motorhome again
Started it up and put it in drive. After it warmed up a bit. I took it on a 5 mile ride speeds 20 -45 mph and things went better then expected👍
Oil temp 196*f @ 800 rpm's stopped at a light 19psi
Oil temp 210*f @ 2200 rpm's cursing at 45mph 43psi
These readings are with the regular 10/30 oil in it. On a 78*f day
Don't think I'm going to use the seafoam stuff I'm not a big fan of "snake oil" stuff and I am just am a little leery of super cleaning a engine. I think I'll try another few oil changes and then go to the thicker oil
After researching this forum, and a few others, I'm thinking of trying Shell Rotella T 15W-40 on my next small trip
Any thoughts?
P.S. Can't thank the responders on this forum enough!!!