Oil filler cap leaks?

[Myrunr2010]

So I have always noticed oil coming down from the oil filler cap. I just always assumed it was just sloppy pours (I used to not use a funnel when adding oil). About 6 months ago I painted my valve cover gaskets when I had them off (since then I've used a funnel), and I still seem to have oil seeping from the filler cap. I assume if it wasn't a continual process then what is on there would have burned off. Anyways, do I just need a new filler cap? Is this in anyways normal? Is there some bigger issue that I am not seeing?

I don't have any pictures right now, although it looks just like what you'd think, an oily residue coming down from the filler cap onto the valve cover gaskets that never dries.

 

[m88tow]

Have you checked your PCV out? It sounds like you are building crankcase pressure and the oil is finding the path of least resistance out out the engine.

 

[Myrunr2010]

Have you checked your PCV out? It sounds like you are building crankcase pressure and the oil is finding the path of least resistance out out the engine.

Well, I replaced the pcv when I did the valve cover gaskets. However, shortly thereafter I put what is essentially an oil catch can on the line from the pcv to the intake bc I was getting oil in the intake. I'm not sure what type of pressures are experienced through that line if that would be enough to cause a pressure increase. I used a compressor moisture separator, which I would think would be more than capable of flowing enough cfm/psi, but I could be wrong. I don't remember if it leaked before I did that or not. What do you think?

 

[m88tow]

You would think that would be ok and would work unless it has become blocked somehow. With the engine running pull out the dipstick and see if you see it pushing out the pressure...usually if it's dark out and you look at that with a flashlight you can see if or if it's daylight and you can see it really well then you know you have some problems. Do a cylinder leak down test to confirm any other engine issues.

 

[LittleCaesar]

Buy a new gasket for it.

 

[Myrunr2010]

Buy a new gasket for it.

Didn't know that was a thing, I doesn't look like there is a gasket on there now. Just your regular old auto parts store carry them?

 

[Myrunr2010]

You would think that would be ok and would work unless it has become blocked somehow. With the engine running pull out the dipstick and see if you see it pushing out the pressure...usually if it's dark out and you look at that with a flashlight you can see if or if it's daylight and you can see it really well then you know you have some problems. Do a cylinder leak down test to confirm any other engine issues.

I'll see it pushing fumes/oil back out of the dipstick hole if there is too much pressure? Otherwise I'm fine?

 

[m88tow]

I'll see it pushing fumes/oil back out of the dipstick hole if there is too much pressure? Otherwise I'm fine?

There will be some usually but if it is excessive then you have issues and should do a leak down test to see where the problem lies.

 

[LittleCaesar]

part# 90430-37140, though it is for a 99, I can't say 100% it is the same for a 97.

 

[atalarico]

I kind of think I have the same symptoms of whatever is going on here. I don't want to make the seal on my oil fill cap any tighter now that I read that it's maybe because of an overpressure situation. I'd rather it be able to vent the pressure through that than something more expensive elsewhere.

Also, can someone explain the PCV to me?

Thanks!

 

[m88tow]

There is not any oil pressure so to speak under the valve covers, good amount of oil being moved around but no pressure. So when you have oil coming out of the full cap you have too much crankcase pressure and it is finding the path of least resistance out of the engine. PCV stand for Positive Crankcase Ventilation. Engines build up pressure and need to be relieved somehow. In the old days it would often be relieved to the atmosphere, this had a few problems because it was at times messy and would actually cause oil to leak on the ground overtime. My old 12 valve Cummins is like this and leaves a few drops out of the breather tube everywhere I park. PCV relieves that pressure back into the intake side of the engine so that the pressure is dropped without the mess.

 

[Myrunr2010]

So I have been theorizing about this. I have oil weeping from the oil filler cap. I also have oil weeping from 2 of the 6 spark plug tube gaskets (I replaced them and still had the issue on 2 of them). Here is the kicker though, I've been having rear main seal issues too. I replaced it when I did the clutch a few months back, and shortly thereafter (2 months ish) I noticed I was losing a LOT of oil (quart every 30 minutes). I pulled the trans to do the seal, once I got everything off, I noticed that the top edge of the seal was sitting ~1/8" proud of where it should, so I replaced it and was very very careful about seal placement and install (who wants to drop the trans a 3rd time?!?). Anyways, got it all buttoned back up, losing a ton of oil immediately. Just got everything back down and the seal is sitting proud (whole thing, all the way around).

So I installed the oil catch cans I was talking about a while back. I'm wondering if they are clogged and now allowing pressure to vent. The whole seal being evenly pushed proud, sounds to me like it would take even pressure from the back side (and a lot of it, that seal is atight fit). What do yall think? Is that possible or do I really suck that bad at RMS install?

 

[ThorInc]

So I have been theorizing about this. I have oil weeping from the oil filler cap. I also have oil weeping from 2 of the 6 spark plug tube gaskets (I replaced them and still had the issue on 2 of them). Here is the kicker though, I've been having rear main seal issues too. I replaced it when I did the clutch a few months back, and shortly thereafter (2 months ish) I noticed I was losing a LOT of oil (quart every 30 minutes). I pulled the trans to do the seal, once I got everything off, I noticed that the top edge of the seal was sitting ~1/8" proud of where it should, so I replaced it and was very very careful about seal placement and install (who wants to drop the trans a 3rd time?!?). Anyways, got it all buttoned back up, losing a ton of oil immediately. Just got everything back down and the seal is sitting proud (whole thing, all the way around).

So I installed the oil catch cans I was talking about a while back. I'm wondering if they are clogged and now allowing pressure to vent. The whole seal being evenly pushed proud, sounds to me like it would take even pressure from the back side (and a lot of it, that seal is atight fit). What do yall think? Is that possible or do I really suck that bad at RMS install?

You are draining the oil catch cans correct?

 

[Myrunr2010]

You are draining the oil catch cans correct?

Well, yes, and no. I don't think enough oil has entered them to fill it, if it had it should still push to the other side (out the exit). It looks like some of the oil in them has cooked, and has put a nasty film over everything, which could be blocking airflow too.

 

[ThorInc]

ideally, I drain mine once amonth and get maybe two teaspoons full. Mine is located against the side of the air box. Moisture is also mixed in and the oil smells burnt but I would expect this and would also expect that the weather and temp can affect the contents. I also added an electrical oil pessure gauge a few years back and that is also helpful to me. I would pick up a new pcv valve and cap and run the suggested tests. Oil should not be normally leaking from the cap.

 

[Myrunr2010]

ideally, I drain mine once amonth and get maybe two teaspoons full. Mine is located against the side of the air box. Moisture is also mixed in and the oil smells burnt but I would expect this and would also expect that the weather and temp can affect the contents. I also added an electrical oil pessure gauge a few years back and that is also helpful to me. I would pick up a new pcv valve and cap and run the suggested tests. Oil should not be normally leaking from the cap.

What is a leakdown test and how is it performed?

 

[ThorInc]

What is a leakdown test and how is it performed?

Here are the results for the search on Google using your exact question:

https://www.google.com/search?q=What+is+a+leakdown+test+and+how+is+it+performed?&ie=utf-8&oe=utf-8

 

[m88tow]

What is a leakdown test and how is it performed?

If you have to ask it will be best to just take it to a reputable shop and let them do it for you. By the time you buy the proper tools to perform it you could have been money ahead letting them do it for you.

 

[Myrunr2010]

If you have to ask it will be best to just take it to a reputable shop and let them do it for you. By the time you buy the proper tools to perform it you could have been money ahead letting them do it for you.

Just because I've never heard of the test doesn't mean I'm not capable of performing it.

 

[m88tow]

Just because I've never heard of the test doesn't mean I'm not capable of performing it.

I didn't say that...you want to buy the gauges to use one time in your life? If you are going to be doing it more than once then yes buy the tools and get going. You need good set of leak down gauges, I prefer the dual gauge mounted in a block( got mine from snap on) and it comes with most common adapters you will need in the automotive world. Also you will need an air compressor.