Engine rebuild?, distributor?, or something else???
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Mountain Pass
Joined: Dec 2013
Posts: 107
Likes: 4
Engine rebuild?, distributor?, or something else???
Hi all.
Having some issues that I am trying to work through.
1986 351 W
Recently installed a new aluminum intake (weiand stealth)
Since then, I am now losing all oil pressure when she warms up.
Before this issue, I never noticed oil pressure go down past half and now, after 5-10 mins of driving it drops to almost zero at idle.
When I am driving and putting a load on, it will go up to around 20-30.
Installed mechanical gauge and it is doing the exact same thing as the stock gauge.
I have read that I could have spun a bearing, or my clearances are off, or engine is just tired, but I find it interesting that this just came to light after installing aluminum intake.
A. What should I check first?
B. Could the distributor be at fault since it drives the oil pump?
C. Do I have to pull the engine to figure this out?
I would have assumed that I would hear knocking or some sort of engine noise if there was a problem, but she seems to run exactly the same as before.
Please help before I bite the bullet and pull the engine. UGH
Thanks all
Having some issues that I am trying to work through.
1986 351 W
Recently installed a new aluminum intake (weiand stealth)
Since then, I am now losing all oil pressure when she warms up.
Before this issue, I never noticed oil pressure go down past half and now, after 5-10 mins of driving it drops to almost zero at idle.
When I am driving and putting a load on, it will go up to around 20-30.
Installed mechanical gauge and it is doing the exact same thing as the stock gauge.
I have read that I could have spun a bearing, or my clearances are off, or engine is just tired, but I find it interesting that this just came to light after installing aluminum intake.
A. What should I check first?
B. Could the distributor be at fault since it drives the oil pump?
C. Do I have to pull the engine to figure this out?
I would have assumed that I would hear knocking or some sort of engine noise if there was a problem, but she seems to run exactly the same as before.
Please help before I bite the bullet and pull the engine. UGH
Thanks all
FTE Legend
Joined: Nov 2015
Posts: 30,940
Likes: 4,125
From: Angier, NC
How many miles on the motor?
When you pulled the intake was there a lot of sludge or hard crap build up?
I am pretty sure no oil goes thru the intake on any motor I have seen / worked on.
Only thing I know that effects oil PSI is bearing clearance, mainly rod & main bearings or a plugged oil pick up screen and why I asked about the sludge / crap.
Lets see what others have to say.
Dave ----
When you pulled the intake was there a lot of sludge or hard crap build up?
I am pretty sure no oil goes thru the intake on any motor I have seen / worked on.
Only thing I know that effects oil PSI is bearing clearance, mainly rod & main bearings or a plugged oil pick up screen and why I asked about the sludge / crap.
Lets see what others have to say.
Dave ----
Thread Starter
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Mountain Pass
Joined: Dec 2013
Posts: 107
Likes: 4
Thank you for the reply.
There is either 55k miles, 155k miles, or 255k miles.
It is a pretty recent purchase.
The guy I bought from (eBay sleezeball - I know, my fault for buying on eBay) said it was original 55k miles, but I say no way.
When I pulled the intake, the inside actually looked pretty nice. I did not see any sludge or anything nasty looking.
I don't think oil goes through the intake either. Just that the distributor has to be removed and reinstalled when the new intake goes in. Maybe something happened with the distributor in that process.
It is firmly down where it is supposed to be.
I am starting to think the engine is a bit tired. It has never really run perfect. I have spent hrs and hrs trying to get it to run the way I think it should.
I honestly do not know what kind of power I should be seeing. I have read that these should be able to tow 6-7k lbs. I am not sure I could tow 2500 lbs.
Maybe it is just time
There is either 55k miles, 155k miles, or 255k miles.
It is a pretty recent purchase.
The guy I bought from (eBay sleezeball - I know, my fault for buying on eBay) said it was original 55k miles, but I say no way.
When I pulled the intake, the inside actually looked pretty nice. I did not see any sludge or anything nasty looking.
I don't think oil goes through the intake either. Just that the distributor has to be removed and reinstalled when the new intake goes in. Maybe something happened with the distributor in that process.
It is firmly down where it is supposed to be.
I am starting to think the engine is a bit tired. It has never really run perfect. I have spent hrs and hrs trying to get it to run the way I think it should.
I honestly do not know what kind of power I should be seeing. I have read that these should be able to tow 6-7k lbs. I am not sure I could tow 2500 lbs.
Maybe it is just time
Lead Driver
Joined: Apr 2002
Posts: 5,342
Likes: 1,248
Seems like you are getting good oil pressure driving around. At idle oil pressure will drop, as low as 5 psi. If this is a high mileage engine you can try Lucas oil treatment which can fill spaces caused by wear and improve oil pressure. I suspect that your guages are not sensitive enough at idle. The stock guage is known to read low at idle. Your after market guage reads 0?
Lead Driver
Joined: Nov 2013
Posts: 7,178
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Is your oil pressure sender mounted directly on the block, or in a stand-off like seen here? (This also shows the oil pressure safety switch I added for my electric fuel pump conversion)
That hex-shaped horizontal piece is hollow inside. It's been a while since I had it off, but there may have been a restrictor where it threads into the block to pick off oil pressure. If equipped with an orifice and it was clogged, that could skew the pressure reading, especially at the lower end of the range.
Lead Driver
Joined: Apr 2002
Posts: 5,342
Likes: 1,248
Few things to consider:
1. What kind of oil are you using?
2. When was your last oil change?
3. What engine temperature are we talking about, I assume warmed up in this discussion.
4. What do your oil pressure sensors register on cold start up?
1. What kind of oil are you using?
2. When was your last oil change?
3. What engine temperature are we talking about, I assume warmed up in this discussion.
4. What do your oil pressure sensors register on cold start up?
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Lead Driver
Joined: Apr 2002
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Another couple thoughts, how's your mpg? If you are running rich and or have low compression, you could have excess blow by, contaminating and thinning your oil resulting in lower viscosity and oil pressure.
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Lead Driver
Joined: Nov 2013
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Was the oil pressure drop immediate after changing the manifold? Or did it take a few days/weeks before you noticed it? Did you also change the carb at the same time? I'd think a different carb would have more of an effect on the air/fuel mix than a manifold change by itself, but who knows.
For troubleshooting, give the engine a fresh oil change and see what happens.
Thread Starter
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Mountain Pass
Joined: Dec 2013
Posts: 107
Likes: 4
Wow, a few things here to answer.
My oil pressure sensors attach like the pic above, but only 1 fitting, so I removed the stock fitting and used it for my new mechanical.
Oil pressure would drop at the same time with both gauges.
At cold start, oil pressure runs at 46.
Answers to Big Blue2
1. I am using Rotella 15w40
2. Oil was very recently changed. I maybe have 20 miles since the change.
3. I would say running temps. It can sit idling in the driveway for 20 minutes. Eventually it will drop. Its when I drive it and really warm it up is when it drops quicker.
4. 46
MPG is around 11 which is not good.
It seemed to run super rich and was really hard to get to run lean. Thats why I have been through 4 different carbs. The Summit 600 is by far the best carb I have run.
My thought was that I was running fuel passed the cylinders therefore thinning my oil. So I figured now was a good time to fix the oil pan gasket and do a full oil change. That did not fix it.
It seems like the oil pressure drop was pretty immediate after the intake change. I usually look at my gauges more than the road haha. However, since this car has never been super reliable, I have other vehicles. I don't drive it that often (which I would love to change)
I hope this answers your questions
My oil pressure sensors attach like the pic above, but only 1 fitting, so I removed the stock fitting and used it for my new mechanical.
Oil pressure would drop at the same time with both gauges.
At cold start, oil pressure runs at 46.
Answers to Big Blue2
1. I am using Rotella 15w40
2. Oil was very recently changed. I maybe have 20 miles since the change.
3. I would say running temps. It can sit idling in the driveway for 20 minutes. Eventually it will drop. Its when I drive it and really warm it up is when it drops quicker.
4. 46
MPG is around 11 which is not good.
It seemed to run super rich and was really hard to get to run lean. Thats why I have been through 4 different carbs. The Summit 600 is by far the best carb I have run.
My thought was that I was running fuel passed the cylinders therefore thinning my oil. So I figured now was a good time to fix the oil pan gasket and do a full oil change. That did not fix it.
It seems like the oil pressure drop was pretty immediate after the intake change. I usually look at my gauges more than the road haha. However, since this car has never been super reliable, I have other vehicles. I don't drive it that often (which I would love to change)
I hope this answers your questions
Lead Driver
Joined: Apr 2002
Posts: 5,342
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All those questions were for you to ponder. Not really my questions. I would say that the pressures you are reporting are all pretty normal, save for warm idle. If you can check your guage using a regulated inflator or compressor that would eliminate the guage fault. I'm guessing the engine is a high miler, or you wouldn't be contemplating a replacement. Your mileage is low so running rich and or compression is a concern. Rotella oil with 20 miles on it is not likely contaminated. Check that guage.
Moderator
Joined: Jan 2001
Posts: 56,997
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From: Virginia
Did he ever say what the warm idle pressure is? If you had a truck that had lights instead of gauges, you would not know anything was wrong until the pressure drops below 5 psi, if that gives you an idea of what the factory was thinking, both Ford and GM used these 5 psi switches.
Your engine may be tired, but it may have a lot of miles left in it.
Your engine may be tired, but it may have a lot of miles left in it.
Thread Starter
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Mountain Pass
Joined: Dec 2013
Posts: 107
Likes: 4
Well I just took her for a 20 mile spin.
First 5 miles are good, then she warms up and then cruising at approx 10-15psi with foot on the throttle.
Take foot off and coast shes at about 5psi.
Stop and sit at idle, shes at 0psi.
I think the gauges are reading correctly. I will empty 2 qts of oil and then toss in 2 qts of Lucas and see what the changes are.
If they help the situation, then I think it can be narrowed down to needing a rebuild.
Then my decisions are drive it for the summer and make it a Fall project or just pull it soon and get it over with. The fear with the later, is if I will need a cylinder bore, new pistons, etc...
Could I get another 50k with a good honing, new rings, cam, bearings, gaskets?
First 5 miles are good, then she warms up and then cruising at approx 10-15psi with foot on the throttle.
Take foot off and coast shes at about 5psi.
Stop and sit at idle, shes at 0psi.
I think the gauges are reading correctly. I will empty 2 qts of oil and then toss in 2 qts of Lucas and see what the changes are.
If they help the situation, then I think it can be narrowed down to needing a rebuild.
Then my decisions are drive it for the summer and make it a Fall project or just pull it soon and get it over with. The fear with the later, is if I will need a cylinder bore, new pistons, etc...
Could I get another 50k with a good honing, new rings, cam, bearings, gaskets?
Moderator
Joined: Jan 2001
Posts: 56,997
Likes: 2,743
From: Virginia
If you have zero psi, you should hear clicking in the top of the engine and sometimes you will hear a faint very low frequency thump like a faint stomp on a wooden floor. 0 psi means no oil is getting to the top of the engine, and it will start clacking and clicking. If you get a low thump, that means the main bearings are worn. If you get a higher knock, that would be the rod bearings. None of this will be very loud unless one of them is really bad. But with 0 psi, various parts will sometimes complain about it.
Don't rely too much on the psi readings, that is just one part of the overall assessment of the engine. You haven't driven it enough to see how much oil is uses correct?
Don't rely too much on the psi readings, that is just one part of the overall assessment of the engine. You haven't driven it enough to see how much oil is uses correct?
Thread Starter
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Mountain Pass
Joined: Dec 2013
Posts: 107
Likes: 4
Thats great to know.
I honestly don't hear a thump, a click, a clack.... nothing.
I, however don't let it run for more than 10 seconds once I see it down that low. I don't want to cause any damage that will cost me later on.
It doesn't use any oil at all. Other than some slight leaks on the underside.
At first startup, I used to get some smoke and black drips out of the exhaust. I am still running a little rich, but I have gotten it down quite a bit. When I was running much richer, the smoke and ick out of the exhaust was much worse until warmed up. Now it is just a little
I honestly don't hear a thump, a click, a clack.... nothing.
I, however don't let it run for more than 10 seconds once I see it down that low. I don't want to cause any damage that will cost me later on.
It doesn't use any oil at all. Other than some slight leaks on the underside.
At first startup, I used to get some smoke and black drips out of the exhaust. I am still running a little rich, but I have gotten it down quite a bit. When I was running much richer, the smoke and ick out of the exhaust was much worse until warmed up. Now it is just a little