engine oil external leaking

[howiewang]

Buick LeSabre 2000
I can see oil on the ground under the engine (left corner near the driver's seat). lost 1 qt/1-1.5week
Already got oil pan gasket, V.C. gasket (valve cover gasket, but not sure), MAP
sensor (is it related to engine oil leak?) changed.

Now, the mechanic tells me it's the intake gasket (is it true? I thought it might cause coolant leak to engine oil, not engine oil external leak)? Any other
possibility/gaskets?

Hate to visit mechanics every few days.

[Blue Bowtie]

An intake gasket leaking at an end might leak only oil (from the lifter valley).

Another possibility is the crankcase vent tube. If the rocker cover gaskets were replaced and the CCV tube was not sealed back into the opening in the cover, some normal oil splash and blowby could push oil out in that general area.

[creslevi]

Originally Posted by Blue Bowtie

An intake gasket leaking at an end might leak only oil (from the lifter valley).

Another possibility is the crankcase vent tube. If the rocker cover gaskets were replaced and the CCV tube was not sealed back into the opening in the cover, some normal oil splash and blowby could push oil out in that general area.

Check the oil pressure sending unit, for leaking, mine was on a 94.
Rick
PS
also what color ? Tran/oil or Engine ?, Also check cooler lines and new valve cover gaskets, they are easily mis aligned on installation

[BNaylor]

Welcome to AF.

It would help to post your mileage.

Were you losing that much oil before the replacement of the oil pan and valve cover gaskets? A MAP sensor could cause an external oil leak if the seal is bad. However it is located on the passenger side of the engine on the right side of the upper intake manifold - UIM and not the driver's side. Also, a bad PCV valve and bad or missing o-ring seals for the PCV could cause an oil loss situation. It is located under the MAP sensor on the UIM. Crankcase ventilation occurs within the UIM due to the design and where the PCV valve is placed in the UIM. So I can see why the mechanic looked in that area.

Depending on your mileage a common problem with a Series II 3800 engine is a leaking rear main seal which would show up as a leak on the driver's side of the engine. Depending on how bad it is you can lose quite a bit of engine oil and in most cases you would see a puddle of engine oil where you park your car.

Best thing to do is a more comprehensive and visual inspection using sufficient lighting to pinpoint the source of the leak even if that means safely jacking the car up and crawling under it. Good luck.

[howiewang]

Originally Posted by BNaylor

Welcome to AF.

It would help to post your mileage.

Were you losing that much oil before the replacement of the oil pan and valve cover gaskets? A MAP sensor could cause an external oil leak if the seal is bad. However it is located on the passenger side of the engine on the right side of the upper intake manifold - UIM and not the driver's side. Also, a bad PCV valve and bad or missing o-ring seals for the PCV could cause an oil loss situation. It is located under the MAP sensor on the UIM. Crankcase ventilation occurs within the UIM due to the design and where the PCV valve is placed in the UIM. So I can see why the mechanic looked in that area.

Depending on your mileage a common problem with a Series II 3800 engine is a leaking rear main seal which would show up as a leak on the driver's side of the engine. Depending on how bad it is you can lose quite a bit of engine oil and in most cases you would see a puddle of engine oil where you park your car.

Best thing to do is a more comprehensive and visual inspection using sufficient lighting to pinpoint the source of the leak even if that means safely jacking the car up and crawling under it. Good luck.

Thank you very much.
I first realized the oil leak @88k miles, early Dec. I inspected the oil level before a 150 miles trip of airport pick-up. It was 1 month after the last oil level check, 4 month and 1800miles after the last oil change. It needed 1 qt oil. I didn't know if there was oil on ground since i'm using apartment parking. There is always something on the ground.

I did oil change after the trip, then I saw oil on the ground. So I brought the car to the mechanics. They told me the oil pan gasket and V C gasket. So I had them changed both of the gaskets. After that, I saw worse oil leak in a couple of days, more oil on ground, lost 3/4 qt oil from Thursday to the following Monday morning. So I brought the car back again, they told me it's oil pan gasket again(?) and they did it for me for free.

It seemed work in the first few days. So I drove to Florida for a vocation in middle Dec. It losted 1 qt oil in 1 week and 1000 miles, followed by another 1 qt in 1 week and 500 miles. I read from the web that 1qt/1000 mile is considered as normal for old engines, but I did see oil on ground. So I brought it back to the mechanics, they told me it's intake manifold gasket in the morming. But when I tried to pick up the car, they told me it's MAP sensor and they changed it. I asked them why i saw the oil on the ground on the driver side. That guy told me the oil might go through the intake manifold because of the bad seal of MAP, then flowed to the driver side and dropped on the ground. However I saw more oil on ground right after I drove 20 min and parked for 1 h. I brought the car back again, they asked me come back after the new year.

I'm really frastrated now. Maybe I should not repair it from the begining. I only need the car for short trip to my school and weekend shopping. But it seems the problem become worse and worse.

I want to know, if I leave it as is, and try to add oil frequently to keep the oil level normal, it is ok?

Appreciate you help. Happy new year!

[howiewang]

Originally Posted by creslevi

Check the oil pressure sending unit, for leaking, mine was on a 94.
Rick
PS
also what color ? Tran/oil or Engine ?, Also check cooler lines and new valve cover gaskets, they are easily mis aligned on installation

Thank you.
they suspected oil pressure sensor at begining. then they told me it's two gaskets.

It's engine oil. It's clear after I change the oil and I did see the low level of engine oil.
It's not difficult to tell if it is misaligned valve cover gasket, right?
Happy new year!

[creslevi]

Originally Posted by howiewang

Buick LeSabre 2000
I can see oil on the ground under the engine (left corner near the driver's seat). lost 1 qt/1-1.5week
Already got oil pan gasket, V.C. gasket (valve cover gasket, but not sure), MAP
sensor (is it related to engine oil leak?) changed.

Now, the mechanic tells me it's the intake gasket (is it true? I thought it might cause coolant leak to engine oil, not engine oil external leak)? Any other
possibility/gaskets?

Hate to visit mechanics every few days.

Hi Howie
I would suspect the valve cover gasket, Like I said before, they are very narrow and especially the back one is very easily misaligned, I know mine was, it's hard to remember a couple years ago all the details but it seems like I ended up going back to the dealer for original equipment gaskets ??, I still have the old ones hanging in the garage and to look at them they are fine but after I changed them the leak stopped, now after a couple years there is still no puddle under the car and it has 246,000 miles on it, if those things are over tightened the gasket will squease out and leak, get a good light and look it over. Good luck and Happy New Year.
Rick

[BNaylor]

In most cases the telltale sign of a bad valve cover gasket either front or rear bank would be oil dripping down to the exhaust manifold and most likely seeing oil burn off or getting a strong smell of burning oil.

The OP should clarify whether the valve cover gaskets were, in fact, replaced and with what brand, if known. It is a no brainer to do a visual inspection.