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| Cleaning the oil pump screen without removing the pan [message #367845] |
Sun, 05 December 2021 19:34  |
Greg C.
Messages: 224
Registered: October 2019
Location: Knoxville, TN
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So on the FB GMC forum, a new owner has just purchased a coach and during his travel home, experienced severe oil pressure loss. He had an oil change done with no better results, and rented a car to drive home. Since his coach is stuck at the airport parking lot in my home town, I offered him the use of my driveway, tools, and assistance to try using thicker oil just to help him get home. Evidently, he lives several hundred miles from here. He's supposed to drive the coach to my house on Tuesday, the way things currently stand. He's decided that the engine has to come out and be rebuilt, but just wants to try to get it home to save the several thousand dollars of towing/hauling. Several folks chimed in on the forum with advice. One or two suggested that oil cookies from the intake may have clogged the oil pump screen since he experienced a rapid loss of oil pressure with no discernible leaks and plenty of oil. Rick Michelhaugh, a local GMC'er, suggested pulling the distributor and spinning the pump backwards with a drill to flush out the screen. My thought on that would be that you would run out of oil quickly sucking it from the galleys and passages instead of the pan, possibly before everything (if there is anything) could be dislodged.
I ran across a device that was patented in 1996, since expired, that consisted of an adapter plate for the oil filter housing, a container of oil that can be pressurized, and assorted plumbing. The patent states that the device will push oil through the housing, through the passages, and backwards through the pump, flushing crud from the screen. Additional valves allow air entrainment of the oil to act as an agitator.
My first thought on that was that the gears in the pump would have such close tolerances as to prevent the oil from flowing past a non-moving gearotor pump, but obviously the guy who spent several thousand dollars to get a patent must have been pretty sure it worked.
So this adapter will be easy to make on my lathe. An old portable air tank can have a screw on lid welded to it for the addition of oil, and some ball valves and hoses would complete the device. The patent called for a maximum pressure of 40 psi to prevent damage to coolers, gaskets, etc.
So I'm going to make the adapter plate so we can flush air through it at the least. If I can find an old air tank and have time to fabricate the rest, I'll do that too before he gets here. I figure the only thing we have to lose is time, and wouldn't it be great if that was the problem and it fixed it?
A question: Is the oil pump screen in such a location that we could look at it through the drain hole with a borescope?
What are everyone's thoughts on this wild goose chase?
Greg Crawford
KM4ZCR
Knoxville, TN
"Ruby Sue"
1977 Royale
Rear Bath
403 Engine
American Eagle Wheels
Early Version Alex Sirum Quad bags
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| Re: Cleaning the oil pump screen without removing the pan [message #367847 is a reply to message #367845] |
Sun, 05 December 2021 20:49  |
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Matt Colie
Messages: 8547
Registered: March 2007
Location: S.E. Michigan
Karma: 7
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Greg,
It should be possible to look at the lube oil pump's pickup through the drain plug, and it would a worth while effort if only to prove that this is not the issue. It would take a lot of something to block that screen up.
I didn't read the FB account (because I gave up on them), but please ask the new owner if the engine had the other symptoms of low lube oil pressure??
Did the lash adjusters get rattly? Did the rod bearings start making noise?
No, you should not be able to blow backwards through the lube oil pump until you exceed the relief spring pressure and that will still not allow much flow.
If the lube oil pressure is gone, spinning the pump backwards might be interesting, but the carbon from the intake has a serious path to get to the pan.
Has anybody checked the pressure sender?? If it were me, the first thing I would do is an electrical diagnosis of the gauge, if that be good, then screw in a cheap mechanical instrument to confirm the pressure.
If the pressure is really gone, drain coolant and lift (with tackle) the intake manifold. If the vehicle sat a long time ignored, it may have developed the problems that cause push rods to buckle. When this happens, lash adjusters (lifters) can get popped out of their place and that is a serious lube oil leak when that happens.
What ever the case, I wish the new owner luck. Be sure to introduce him the "net". There is help here.
Keep us apprised of this situation.
Matt
Matt & Mary Colie - Chaumière -'73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan with OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Near DTW - Twixt A2 and Detroit
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| Re: Cleaning the oil pump screen without removing the pan [message #367849 is a reply to message #367845] |
Sun, 05 December 2021 21:27 |
Greg C.
Messages: 224
Registered: October 2019
Location: Knoxville, TN
Karma: 0
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Thanks Matt. I was hoping you would chime in. He did say he has valve train clatter. It may be that the coach won't make it to my house. It's a good 20 miles. I guess we'll find out.
Greg Crawford
KM4ZCR
Knoxville, TN
"Ruby Sue"
1977 Royale
Rear Bath
403 Engine
American Eagle Wheels
Early Version Alex Sirum Quad bags
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| [GMCnet] Re: Cleaning the oil pump screen without removing the pan [message #367850 is a reply to message #367847] |
Sun, 05 December 2021 21:27 |
Dave Stragand
Messages: 307
Registered: October 2017
Karma: 0
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Ditto on checking the sender. My 2008 Dodge almost gave me a heart attack when it suddenly dropped all oil pressure. The “secret menu” on the gauge cluster showed 0 PSI at idle, and only about 5 PSI when moving. As there was no other sign of lost pressure, I limped home carefully, and soon found that a bad sender was pretty common for my year’s motor. I replaced the sender and all was well. A new sender isn’t a big expense so it’s worth trying!
-Dave
1978 Transmode near Pittsburgh
> On Dec 5, 2021, at 9:50 PM, Matt Colie wrote:
>
> Greg,
>
> It should be possible to look at the lube oil pump's pickup through the drain plug, and it would a worth while effort if only to prove that this is
> not the issue. It would take a lot of something to block that screen up.
>
> I didn't read the FB account (because I gave up on them), but please ask the new owner if the engine had the other symptoms of low lube oil pressure??
>
> Did the lash adjusters get rattly? Did the rod bearings start making noise?
>
> No, you should not be able to blow backwards through the lube oil pump until you exceed the relief spring pressure and that will still not allow much
> flow.
> If the lube oil pressure is gone, spinning the pump backwards might be interesting, but the carbon from the intake has a serious path to get to the
> pan.
>
> Has anybody checked the pressure sender?? If it were me, the first thing I would do is an electrical diagnosis of the gauge, if that be good, then
> screw in a cheap mechanical instrument to confirm the pressure.
>
> If the pressure is really gone, drain coolant and lift (with tackle) the intake manifold. If the vehicle sat a long time ignored, it may have
> developed the problems that cause push rods to buckle. When this happens, lash adjusters (lifters) can get popped out of their place and that is a
> serious lube oil leak when that happens.
>
> What ever the case, I wish the new owner luck. Be sure to introduce him the "net". There is help here.
> Keep us apprised of this situation.
>
> Matt
>
>
> --
> Matt & Mary Colie - Chaumière -'73 Glacier 23 - Members GMCMI, GMCGL, GMCES
> Electronically Controlled Quiet Engine Cooling Fan with OE Rear Drum Brakes with Applied Control Arms
> SE Michigan - Near DTW - Twixt A2 and Detroit
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
_______________________________________________
GMCnet mailing list
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1978 Transmode (403)
Pittsburgh, PA
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| Re: Cleaning the oil pump screen without removing the pan [message #367851 is a reply to message #367845] |
Sun, 05 December 2021 21:47 |
Greg C.
Messages: 224
Registered: October 2019
Location: Knoxville, TN
Karma: 0
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Senior Member |
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I'm not positive from his communication, but he seemed to indicate he had checked the pressure with a mechanical gauge. And he did say he has valve train clatter. As Matt said it could have varnish on the valve stems with corresponding bent pushrods.
Greg Crawford
KM4ZCR
Knoxville, TN
"Ruby Sue"
1977 Royale
Rear Bath
403 Engine
American Eagle Wheels
Early Version Alex Sirum Quad bags
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| Re: Cleaning the oil pump screen without removing the pan [message #367856 is a reply to message #367845] |
Mon, 06 December 2021 14:53 |
JohnL455
Messages: 4447
Registered: October 2006
Location: Woodstock, IL
Karma: 12
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The pickup can get clogged with carbon, errant silicone etc. like your kitchen sink strainer, but GM put a spring loaded bypass flapper door on the face of the screen to allow un screened oil into the pump in just such event. So “That ain’t it”
If ticking I would guess oil pressure is low as elec gauge suggests. But I would confirm.
I would not put heavier oil in but instead just 10W-30. Thicker oil will he harder to intake and pump.
I’d drain oil, change filter and cut open old to inspect (could also be restricted and then bypass could allow chunks into places that will kill the bearings.
Is it misfiring? Suggesting bent push rods? Why not just pull valve covers and inspect/observe.
John Lebetski
Woodstock, IL
77 Eleganza II
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| Re: Cleaning the oil pump screen without removing the pan [message #367862 is a reply to message #367845] |
Tue, 07 December 2021 13:23 |
Greg C.
Messages: 224
Registered: October 2019
Location: Knoxville, TN
Karma: 0
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Senior Member |
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I do dislike the instant message way of communicating. I have given him my phone number, but he hasn't called for an actual conversation as of yet. Right now, he's driving here to Knoxville from Raleigh tomorrow and we are scheduled to do an oil change on Thursday morning. He said that he had called 6 people near by on the Black List, and left two messages where there was an opportunity to do so, but no one had called him back.
So I found this out: He purchased the coach in April, then drove it home, about 250 miles. Then a couple of hundred miles around there to shake out some minor issues. A 300 mile trip in August, then 700 miles from Iowa to Tennessee, which is when the issue started. He says the factory gauge shows about half during operation, but when easing off the gas going down hill, it drops to 1/4 and he hears some tappet noise. I think that's when he got the oil changed somewhere along the way, and with no improvement, parked it at the Knoxville Airport, which is where it is now. He says the oil is full, and looks clean. And he has purchased a mechanical oil gauge, but has not hooked it up to check the actual pressure. I will do that when he arrives. It's very helpful to have everyone's input before we actually start on it. Any other thoughts?
Greg Crawford
KM4ZCR
Knoxville, TN
"Ruby Sue"
1977 Royale
Rear Bath
403 Engine
American Eagle Wheels
Early Version Alex Sirum Quad bags
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| Re: Cleaning the oil pump screen without removing the pan [message #367864 is a reply to message #367845] |
Tue, 07 December 2021 16:13 |
JohnL455
Messages: 4447
Registered: October 2006
Location: Woodstock, IL
Karma: 12
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“He says the factory gauge shows about half during operation, but when easing off the gas going down hill, it drops to 1/4 and he hears some tappet noise.”
This is very odd.
What happens in park when you slowly raise RPM from idle to say 2000 RPM?
You did read my post about the pickup screen having a bypass trap door right?
John Lebetski
Woodstock, IL
77 Eleganza II
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| Re: Cleaning the oil pump screen without removing the pan [message #367877 is a reply to message #367845] |
Wed, 08 December 2021 14:30 |
Greg C.
Messages: 224
Registered: October 2019
Location: Knoxville, TN
Karma: 0
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John, yes, I read your post. Thank you. The coach is not here yet, so I can't answer your question. I'll try that tomorrow if he shows up here. I haven't received any updates from him today.
I plan on listening to it when it gets here, and plumbing in a mechanical gauge for pressure readings at various RPM. No sense in further speculation until we lay eyes/ ears on it.
Greg Crawford
KM4ZCR
Knoxville, TN
"Ruby Sue"
1977 Royale
Rear Bath
403 Engine
American Eagle Wheels
Early Version Alex Sirum Quad bags
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| Re: Cleaning the oil pump screen without removing the pan [message #367878 is a reply to message #367845] |
Wed, 08 December 2021 14:33 |
Greg C.
Messages: 224
Registered: October 2019
Location: Knoxville, TN
Karma: 0
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John, yes, I read your post. Thank you. The coach is not here yet, so I can't answer your question. I'll try that tomorrow if he shows up here. I haven't received any updates from him today.
I plan on listening to it when it gets here, and plumbing in a mechanical gauge for pressure readings at various RPM. No sense in further speculation until we lay eyes/ ears on it.
Oops. Just got an instant message from him. He can't get here until next week.
Greg Crawford
KM4ZCR
Knoxville, TN
"Ruby Sue"
1977 Royale
Rear Bath
403 Engine
American Eagle Wheels
Early Version Alex Sirum Quad bags
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| Re: Cleaning the oil pump screen without removing the pan [message #367886 is a reply to message #367845] |
Wed, 08 December 2021 18:19 |
Greg C.
Messages: 224
Registered: October 2019
Location: Knoxville, TN
Karma: 0
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Thanks, John. I had actually spent a few minutes on the lathe for the project, but I will hold off finishing anything. I'm hoping for his sake that whatever the problem may be, it turns out to be minor. I know that hauling the coach all the way to Raleigh from Knoxville is going to cost a fortune.
Greg Crawford
KM4ZCR
Knoxville, TN
"Ruby Sue"
1977 Royale
Rear Bath
403 Engine
American Eagle Wheels
Early Version Alex Sirum Quad bags
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| Re: Cleaning the oil pump screen without removing the pan [message #367890 is a reply to message #367886] |
Wed, 08 December 2021 20:40 |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
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Greg C. wrote on Wed, 08 December 2021 18:19Thanks, John. I had actually spent a few minutes on the lathe for the project, but I will hold off finishing anything. I'm hoping for his sake that whatever the problem may be, it turns out to be minor. I know that hauling the coach all the way to Raleigh from Knoxville is going to cost a fortune.
I'm just watching this from afar but in your Dec 7th posting you say the coach is at the Knoxville airport. Then today you say it is in Raleigh. If it is in Knoxville and you are in Knoxville, then I would go hire a tow truck for a local tow OR do what I did.
My daughter and I towed mine home with my Colorado Pickup just under 70 miles. We towed it after midnight and had no traffic with only 3 red stop lights along the way. She was driving the Colorado and set the cruise control at 55 mph. It took us about 1 hour and 30 minutes. The hardest thing was getting it backed into our hangar.
Those are just some ideas if the coach is currently in the Knoxville area. I would tow it for you if you were nearer to me. I would not attempt a personal tow if it is in Raleigh (350 miles or so).
Ken B.
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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| Re: Cleaning the oil pump screen without removing the pan [message #367963 is a reply to message #367845] |
Sat, 11 December 2021 21:17 |
Greg C.
Messages: 224
Registered: October 2019
Location: Knoxville, TN
Karma: 0
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Ken:
I am sorry about not being more clear in my ramblings. The coach is in Knoxville. The owner was attempting to drive it from his old home in Iowa to his new domicile in Raleigh. Once it showed the presumed oil pressure issue, he stopped somewhere and had the oil changed. This did not help anything. He parked it in a long term lot near the Knoxville airport and drove a rented car home. He was looking for some help and a place to change to a higher viscosity oil in an attempt to drive it to Raleigh. He has assumed that the engine will need a rebuild, and didn't think he had much to lose by trying the thicker oil, since if it doesn't work he will have to pay several thousand dollars to have it hauled to his home in Raleigh. I saw his postings on Facebook, and offered my driveway and assistance for the experiment. The last I heard, he is supposed to be driving back to Knoxville Monday, and attempt to drive the coach about 25 miles to my house. That's where it stands at the moment.
Greg Crawford
KM4ZCR
Knoxville, TN
"Ruby Sue"
1977 Royale
Rear Bath
403 Engine
American Eagle Wheels
Early Version Alex Sirum Quad bags
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| Re: Cleaning the oil pump screen without removing the pan [message #367967 is a reply to message #367845] |
Sun, 12 December 2021 09:18 |
JohnL455
Messages: 4447
Registered: October 2006
Location: Woodstock, IL
Karma: 12
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I don’t think you state what oil was used at the oil change. Maybe the owner can shed some light with a receipt. Again, going heavier viscosity is the wrong approach in my opinion, as it is more resistant to flow by definition. But first we need to know what’s in there.
John Lebetski
Woodstock, IL
77 Eleganza II
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| Re: Cleaning the oil pump screen without removing the pan [message #367981 is a reply to message #367845] |
Sun, 12 December 2021 17:40 |
jhbridges
Messages: 8412
Registered: May 2011
Location: Braselton ga
Karma: -74
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If there's lifter noise, I wouldn't run it, I'd tow it the twenty miles like someone said, late at night. (Actually was it me I'd ask Chuck Boyd if I could borrow a parking space to work on it) Once there I'd do the mechanical gauge thing and if it showed low or zero at idle, I'd hoist the intake. If all the lifters are in place and all the pushrods are straight and unjammed, the engine's gotta come out. Depending how long the coach sat when he bought it, starting and running without preoiling may have opened up bearing clearance. Hope it's something simple, but out of oil pressure is likely to end a 20 mile ride early.
--johnny
Foolish Carriage, 76 26' Eleganza(?) with beaucoup mods and add - ons.
Braselton, Ga.
I forgive them all, save those who hurt the dogs. They must answer to me in hell
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| Re: Cleaning the oil pump screen without removing the pan [message #368038 is a reply to message #367845] |
Wed, 15 December 2021 16:15 |
Greg C.
Messages: 224
Registered: October 2019
Location: Knoxville, TN
Karma: 0
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Senior Member |
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Okay, here's the update. He arrived today about 11:15. It did not sound bad, except for some exhaust leaks. It's a 76 Glenbrook with 93,000 miles on it. The first thing we did was remove the oil pressure sender and plumb in a mechanical gauge. It took a bit for the black looking oil to spiral up the plastic tubing, but it did, and hit about 15 psi. I mentioned that the oil looked really black for having just been changed. He replied "But it looks really clean on the dipstick" and pulled out the transmission dipstick to show me. I gently informed him that the engine oil dipstick was up front under the driver's side hatch. I went out there and pulled the stick. No oil showing. He was very upset that he had paid someone to change the oil (in Iowa, 800 miles ago) and they did not. He had mistakenly been checking the transmission. Finding it low once, he added a quart of engine oil (out front, in the correct place). We all know how the transmission level fluctuates between running/not running/sitting. I had some new oil of various viscosities and I dumped in three quarts. Now it was about a half quart low. Fired it up, and low and behold! We have about 30 PSI at idle rising to 45 at about 2500 rpm. No unusual engine noises. We ran it for a bit, then drained the oil, changed the filter (A FRAM!), primed the new Wix filter, and dumped in five quarts of Mobil 1 10W30. Oil pressure is still good.
I cut open the Fram, and found a lot of grit in the bottom of the filter that appears to be ferrous metal, since a magnet attracts it. I showed this to him, and told him to plan on an engine rebuild in the near future.
I next observed that the radiator overflow reservoir hose was missing. I found it laying nearby, cracked and brittle. We installed a new hose, clamps, and added about a half gallon of antifreeze mixture to top off the radiator. We put a screw in one of his T skirts that was swinging in the breeze. He said he had good brakes, and the people who were supposed to have changed the oil had put new brake lines on it and bled the brakes, and he was happy with the brake situation. It doesn't miss going down the road, and runs okay. He said that it wouldn't go much over 65 or 70 going up some of the hills coming into East Tennessee. Since he was loaded up with stuff from his house for moving, I told him it was probably fine. So I asked if he needed anything else, wished him luck and sent him on his way to Raleigh. I hope everything goes good for him. That's my story. Thanks everyone for exercising the gray matter in our speculation. When he said it was full of oil, I had to take him at his word until it got here.
Greg Crawford
KM4ZCR
Knoxville, TN
"Ruby Sue"
1977 Royale
Rear Bath
403 Engine
American Eagle Wheels
Early Version Alex Sirum Quad bags
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