86 Bonneville oil light 6 cylinder

[greywolf_25]

Hey everybody, just got this Bonneville an its been sitting a while. But I finally got it on the road an it drives great but the oil light comes on randomly when I drive for a while. First time it happened I panicked an rushed the car home an few minutes later I crank it up an its off. I dont hear any knocking or anything but I sat it back down just in case til I get payed to fix it. how would I check to see if its the oil pressure sensor an I guess where to start looking for problems cause I've never had to work on something like that. Thanks in advance.

 

[EaOutlaw]

Hi welcome to the forum,
Well the best place to start on a problem like this is to check the basics.

Does the car have oil in it?

At this point the goal is to determine if the problem is electronic, possible loose connection at the sending unit or a bad sending unit. or is the engine really loosing oil pressure?

Find the oil sending unit on your car is the connector plugged in properly?

Normally located near the oil filter it should look like a bell with a single wire going to it.

Does the sending unit look damaged or is it leaking?

Does the dip stick have lots of crusty dried black oil on it will kind of look like coffee grounds?

Take the oil cap off and look under the cap and inside the opening, does both the cap and what you can see inside the opening look clean?

If you are unsure try to get pictures of what you see and post pictures of what you see.

Does the car have a oil light and a oil pressure gauge? if it has a gauge also what does it show for oil pressure when you first start it cold, once warmed up and driving down the road?

Please go by memory when responding,do not drive or run the car until you determine the engine is producing sufficient oil pressure to the engine at idle and off idle with a known functioning oil pressure test gauge.

You can get one from nearly any good auto parts store as part of their tool loaner program, you buy a used tool from them use it and return it for a full refund when your done. Napa and Auto zone have these programs other Auto Parts stores do the same thing. you have to check around.

the test kit will look like the one in this link from Amazon

http://www.amazon.com/Engine-Pressu...448148638&sr=8-3&keywords=oil+pressure+tester


If it is not a electronic issue, these V6 engines and any engine as old as yours is may have debris either in the oil pan that gets that gets sucked up into the oil pick up tube strainer while driving at a decent speed for a length of time causing the light to flicker or come on all the time while at that speed, once the car is shut off the debris falls back out of the strainer clearing the screen. once you start it up the light stays off and things seem normal.

The second possibility is debris could also be in the cylinder head clogging up the oil return holes, At idle things seem normal because there is not much oil flowing to the top of the engine at idle, once you drive faster down the road the clogged up oil drain holes cannot flow enough oil back to the oil pan fast enough to keep up with the demand, so the light will flicker or come one all the time while at that speed.

This would mean while you are driving down the road keeping up with traffic on the valve covers are filling up with oil starving the pump and engine of oil

if either of these two things are in fact what is happening to your car, Do not panic because either situation or both situations at the same time can be fixed by you with basic hand tools and elbow grease,and yes some parts.

the debris I am speaking of could be caused from a few things the first of the two likely culprits are if the previous owner didn't change the oil on a regular basis and only used the car for short trips the oil could have turned to a thick sludge which sticks to everything and eventually dries up in to a mess all throughout the engine, This mess will look like the used but black coffee grounds.

the second situation could be from the original timing chain set that GM used to help make the engine nice and quiet, this timing chain set had gears that had this fibrous plastic coating on the cam gear that would eventually spider crack and fall apart in chunks ending up in the oil pan.

At one point if the timing chain was changed to a better all metal timing chain set and the mechanic whom worked on it didn't remove the oil pan to clean it out this debris could be in there for years and never cause the owner any problems if they didn't drive the car fast enough to suck up this debris in the oil pan.

It could be the original timing chain in the car that has never been replaced that is simply falling apart like mentioned and needs to be replaced.

I will write more information that will help you once you respond to the few questions asked.

If you have checked the basics and do not see anything obvious, I would start with a oil and filter change for diagnostic purposes So purchase the correct weight oil for your car and ambient temperature your car encounters.

For now purchase inexpensive oil because you may need to dump it and change it again if you find debris like mentioned in the pan or valve covers.
or find out that you need to change the timing chain.

Some of this oil will be used to help determine what if anything is in the oil pan.
Continued in second post.

 

[EaOutlaw]

If you made it this far you will be getting ready to do a oil and filter change.

When you buy this inexpensive oil buy at least a case,the few different steps you will need to take doing this oil change is filter or strain the oil that comes out of the engine,

For this find a piece of window screening and cut a large piece to cover your drain pan with.

Then drain your oil like normal into the pan, have your drain plug ready to put back in just in case the oil doesn't drain fast enough through the screening.

Once the oil stops flowing have a coat hanger or thin metal rod bent so you can stick it in the oil pan and scrape the bottom of the pan trying to drag some of this potential debris out of the pan.

Make sure anything that comes out of the engine gets strained through the screen in the drain pan.

If you find anything on the screen covering the pan grab some of it with your thumb and index finger and roll it around while squeezing it, does the debris just fall apart or does it feel solid like broken pieces of plastic?

if it is solid like plastic you will have to determine the condition of the timing chain and gears.

I will help you further once we determine what road we are going down.

For now work on the basics and post your findings so I will and others here know what information to provide you.

BTW if you or anyone that reads this have never performed a oil change before.

When you go to change the oil filter, if we get to that point make sure to compare the new oil filter to the old one.

Make sure they are the same size both length and width,and the filter seal matches up exactly with the old one .

When replacing the oil filter always fill the filter up with oil let it sit and the air bubbles escape rub a little oil on the seal and clean the mating surface with a clean rag on the engine.

Do not worry about spilling a little oil or making a mess its best to have oil in the filter, than put one on dry. just clean the mess and wipe down the filter if needed. once the filter is tightened down properly.

Some of what I write here is not just for you, its is for anyone that needs help working on their car many people have never changed their own oil or done anything to their cars so please do not get offended if you consider this obvious.

If you are unsure of anything ask, the only dumb question is the one you know the answer to, or the one your should have asked and didn't.

 

[greywolf_25]

Hi welcome to the forum,
Well the best place to start on a problem like this is to check the basics.

Does the car have oil in it?

At this point the goal is to determine if the problem is electronic, possible loose connection at the sending unit or a bad sending unit. or is the engine really loosing oil pressure?

Find the oil sending unit on your car is the connector plugged in properly?

Normally located near the oil filter it should look like a bell with a single wire going to it.

Does the sending unit look damaged or is it leaking?

Does the dip stick have lots of crusty dried black oil on it will kind of look like coffee grounds?

Take the oil cap off and look under the cap and inside the opening, does both the cap and what you can see inside the opening look clean?

If you are unsure try to get pictures of what you see and post pictures of what you see.

Does the car have a oil light and a oil pressure gauge? if it has a gauge also what does it show for oil pressure when you first start it cold, once warmed up and driving down the road?

Please go by memory when responding,do not drive or run the car until you determine the engine is producing sufficient oil pressure to the engine at idle and off idle with a known functioning oil pressure test gauge.

You can get one from nearly any good auto parts store as part of their tool loaner program, you buy a used tool from them use it and return it for a full refund when your done. Napa and Auto zone have these programs other Auto Parts stores do the same thing. you have to check around.

the test kit will look like the one in this link from Amazon

http://www.amazon.com/Engine-Pressu...448148638&sr=8-3&keywords=oil+pressure+tester


If it is not a electronic issue, these V6 engines and any engine as old as yours is may have debris either in the oil pan that gets that gets sucked up into the oil pick up tube strainer while driving at a decent speed for a length of time causing the light to flicker or come on all the time while at that speed, once the car is shut off the debris falls back out of the strainer clearing the screen. once you start it up the light stays off and things seem normal.

The second possibility is debris could also be in the cylinder head clogging up the oil return holes, At idle things seem normal because there is not much oil flowing to the top of the engine at idle, once you drive faster down the road the clogged up oil drain holes cannot flow enough oil back to the oil pan fast enough to keep up with the demand, so the light will flicker or come one all the time while at that speed.

This would mean while you are driving down the road keeping up with traffic on the valve covers are filling up with oil starving the pump and engine of oil

if either of these two things are in fact what is happening to your car, Do not panic because either situation or both situations at the same time can be fixed by you with basic hand tools and elbow grease,and yes some parts.

the debris I am speaking of could be caused from a few things the first of the two likely culprits are if the previous owner didn't change the oil on a regular basis and only used the car for short trips the oil could have turned to a thick sludge which sticks to everything and eventually dries up in to a mess all throughout the engine, This mess will look like the used but black coffee grounds.

the second situation could be from the original timing chain set that GM used to help make the engine nice and quiet, this timing chain set had gears that had this fibrous plastic coating on the cam gear that would eventually spider crack and fall apart in chunks ending up in the oil pan.

At one point if the timing chain was changed to a better all metal timing chain set and the mechanic whom worked on it didn't remove the oil pan to clean it out this debris could be in there for years and never cause the owner any problems if they didn't drive the car fast enough to suck up this debris in the oil pan.

It could be the original timing chain in the car that has never been replaced that is simply falling apart like mentioned and needs to be replaced.

I will write more information that will help you once you respond to the few questions asked.

If you have checked the basics and do not see anything obvious, I would start with a oil and filter change for diagnostic purposes So purchase the correct weight oil for your car and ambient temperature your car encounters.

For now purchase inexpensive oil because you may need to dump it and change it again if you find debris like mentioned in the pan or valve covers.
or find out that you need to change the timing chain.

Some of this oil will be used to help determine what if anything is in the oil pan.
Continued in second post.

Thanks for the reply an, the dip stick say's its full of oil but I took the valve cover off an there's a small puddle of oil here an there but the rocker arms are just bone dry. But the oil is not crusty or anything. So does that mean there might be a little sludge build up at the top end? Or should I change the strainer just to be safe?

______________________________

 

[melsg5]

The strainer is inside the oil pan, major job and you haven't verified if you have a bad sender. Have you rented or purchased a oil pressure gauge to see what is really going on. I assume you changed the oil and filter when you got the car and are using 10W30 oil?

 

[EaOutlaw]

if you have the valve cover off which is not what I was expecting you to do. the puddles of oil may be normal if those puddles do not have a drain hole under it.

If the covers are still off. look at the front and back or the head close to the exhaust near the corners of the head for the drain holes, if they are clear and you can see down into the hole they should be fine. if your unsure take some close up pictures.

Do not do anything else to avoid more work than necessary. the problem needs to be diagnosed as mentioned in my first post. this is easy to do.

If you have other problems why you can not do these diagnostic steps please communicate this to us so we can help you in the way you need.

 

[greywolf_25]

update

If you made it this far you will be getting ready to do a oil and filter change.

When you buy this inexpensive oil buy at least a case,the few different steps you will need to take doing this oil change is filter or strain the oil that comes out of the engine,

For this find a piece of window screening and cut a large piece to cover your drain pan with.

Then drain your oil like normal into the pan, have your drain plug ready to put back in just in case the oil doesn't drain fast enough through the screening.

Once the oil stops flowing have a coat hanger or thin metal rod bent so you can stick it in the oil pan and scrape the bottom of the pan trying to drag some of this potential debris out of the pan.

Make sure anything that comes out of the engine gets strained through the screen in the drain pan.

If you find anything on the screen covering the pan grab some of it with your thumb and index finger and roll it around while squeezing it, does the debris just fall apart or does it feel solid like broken pieces of plastic?

if it is solid like plastic you will have to determine the condition of the timing chain and gears.

I will help you further once we determine what road we are going down.

For now work on the basics and post your findings so I will and others here know what information to provide you.

BTW if you or anyone that reads this have never performed a oil change before.

When you go to change the oil filter, if we get to that point make sure to compare the new oil filter to the old one.

Make sure they are the same size both length and width,and the filter seal matches up exactly with the old one .

When replacing the oil filter always fill the filter up with oil let it sit and the air bubbles escape rub a little oil on the seal and clean the mating surface with a clean rag on the engine.

Do not worry about spilling a little oil or making a mess its best to have oil in the filter, than put one on dry. just clean the mess and wipe down the filter if needed. once the filter is tightened down properly.

Some of what I write here is not just for you, its is for anyone that needs help working on their car many people have never changed their own oil or done anything to their cars so please do not get offended if you consider this obvious.

If you are unsure of anything ask, the only dumb question is the one you know the answer to, or the one your should have asked and didn't.

Ok I'm back. An If I haven't said it thanks to the both of you because you helped me to at least get started on where to look. Just did the oil treatment an no debris' but the oil was just black an gritty, kinda slimy. Still some traces of the old oil because the new oil is a little dark but alot cleaner then it was. An I also noticed a couple of drops of oil under the car but nothing major. Also have a small valve cover gasket leak. Not sure if that helps but just for the sake of knowledge Still a oil light but it never comes on immediately after I start the car. Car still runs fine but In the morning I'll do a oil pressure test an really find out what's going on. First time doing this ,so as far as the Motor goes what type of pressure range is good? I have the 231 6 cylinder an the car has roughly 130,000 miles on it. An just to make sure I'm looking in the right spot would the sending unit be near the oil filter?

 

[EaOutlaw]

It has been way too many years for me to remember these specific things.
Which is why I suggested you to get a manual.

You will need a manual with our suggestions to know what to do. without one you will cause more problems than you have.

The oil sending unit is designed to trigger a oil light to come on I think below 8 psi, I am not exactly sure which is why you need a manual.

you will have to look around for the oil sending unit. Look it up at Napa auto parts once you know what it looks like it will be easier to find.

If you do not locate a manual and your not experienced we do not stand a chance of helping you.

Again do not run the car until you find out if the problem is electrical or mechanical.

______________________________

 

[melsg5]

a good rule of thumb is at least 10psi per 1000 rpm

 

[greywolf_25]

a good rule of thumb is at least 10psi per 1000 rpm

Ok I've check Autozone, advance auto an Napa an they didn't have a oil pressure gauge but I ordered one an it will be here tomorrow. The Napa that has one us about 30 min away. But in the mean time the oil sending unit was only $8 bucks so I bought one an installed it. An now the oil light is on constant instead of just popping up after a little time goes by. I'll have the gauge tomorrow but does this mean anything? Also the connector to the unit is a little brittle but it plugs up kinda snug. And the car is a 86 but the sender unit was labeled as a 87 at the autozone but everything matched right up on the car

 

[EaOutlaw]

well it means you are on the right track and found the oil sending unit on the car that is the one controlling the light.

It should have been a single wire connector right?

If the light went off before and flickered going down the road, now the light is on all the time when it is running you either did not get it plugged back on properly, or your engine just is not making correct oil pressure all the time.

Or the new sending unit is not working properly.

Did you tighten it with the bell or near the base by the threads of the sending unit.

if you tightened it down wrong you could have twisted the bell and torn the internal wiring making the sending unit worthless.

Again this is covered in the factory manual that you keep ignoring.

if there is not enough room for a wrench to tighten the bell you will need a special tool that wraps around the bell securing to the base near the threads.

I promise you if you ignore the elephant in the room about the manual, you will not here from me again.

 

[melsg5]

did you check on the autozone site if they gave you the correct part number?

______________________________

 

[greywolf_25]

did you check on the autozone site if they gave you the correct part number?

I had to order the manual cause they only had c& h body books. Got a new sensor and it did the same thing. But I took the gauge cluster out an the little copper strips that goes to the oil light is damaged an somebody rigged it up with a wire wedged in there to keep a connection to it. It looked like it was falling off.

 

[greywolf_25]

I had to order the manual cause they only had c& h body books. Got a new sensor and it did the same thing. But I took the gauge cluster out an the little copper strips that goes to the oil light is damaged an somebody rigged it up with a wire wedged in there to keep a connection to it. It looked like it was falling off.

I talked to the guy I bought if from an he said he had a back yard machanic do some electrical work to it in the past to fix a heat issue.

 

[EaOutlaw]

well at this point if your good with a soldering iron, you may be able to solder in a insulated jumper wire to get past this severed connection. but take pictures of what you are talking about.