Oil leak

Recently purchased a 47 Chevy 350/350.....if you let the car sit and idle, no issues. But if you drive it any distance, park it and check under it a half hour later there is oil on the ground is 6-7 spots. Mostly coming off the transmission. I cleaned the back of the valve covers, the block below the intake, the oil pan before I drove it last and there is no sign of a leak. Dropped the flywheel shield no oil. Im at a loss, anyone have an issue like this before?

 

what oil is leaking? motor oil or ****** fluid? a th350 has many places that could leak.....the front seal , rear seal , pan gasket , speedo drive , governor cover , shift shaft seal , kickdown , oil fill tube , cooler lines

clean up those areas , and keep an eye on them to see what is leaking

 

its motor oil. must be blowing back on to the transmission while im driving it.

 

motor oil....then check your rear intake manifold end gasket, or could even be the oil pressure sender

 

rear main seal?

 

Oil pressure gauge, electrical or mechanical?

Check the sending unit, or the capillary tube fittings.

 

If its a crate motor, make sure the little plug is in the dipstick hole you aren't using .

 

You are running a PCV valve right, if not the pressure inside the engine is pushing oil out.

 

mechanical gauge...so it should be obvious even at an idle if the line is cracked or broke. the gravel shield is clean inside and out so do you still think is the rear main??

 

yes on the pcv and no its not a crate motor

 

Make sure its in there any way.

There should be a trail headed back up you'd think.
put some UV die in the oil and check it.

 

will do...thanks for all the ideas!!

 

Yoiu seem to have all the answers, yet you are here asking us questions aren't you?

The plastic line has a fitting that can have 2 places for leaks to occur, without any damage/cracks to the line whatsoever.

I was also going to tell you to check the distributor base gasket, but you seem to know everything.

And please enlighten us as to why your engine would have the same oil PRESSURE at idle as it does driving down the road, this should be a good story.

I guess it should be OBVIOUS.

 

Since all the suspect areas have been mentioned except the oil filter, I'm thinking the oil filter is the culprit.

 

Damn Traditions who **** in your wheaties???? Ive had broken and cracked oil pressure lines. let the motor idle for 10 minutes with one and see if you can find that leak.

 

I had one like that and it turned out to be the dipstick tube. Not a drip at idle, then after driving it would leak along the block to head surface in the crack and flow back to the trans and drip. I gave the dipstick tube a good tap with a mallet and it seated, problem solved. Like the others said though, more likely oil pressure fitting or rear manifold?

 

Oil sending unit or bad fitting on oil pressure line doesn't always leak at idle,but will leak when engine is at higher rpms and under a load.Clean the thing up ,drive it and find the leak. I have even seen people put powder on an engine to track an oil leak. Then fix leak and clean it up.

 

Harmonic balancer. Needs a speedy sleeve.

 

You're gonna laff but, check the bolt that belongs in the fuel pump pushrod hole, its a little short guy. Mine only leaked when driven, never at idle, took awhile to find it.

 

Clean every surface from the back of the manifold down including the back of the heads. A good wipe with a rag with any solvent will do. Then dust every surface you can reach with tal*** powder. Take it for a run, park it and watch for an oil trail in the powder.

Bob

 

Are you sure it's oil? Could be the seal on the kick down. It will leak when parked but not when running...


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Good idea on the powder.

Clean the whole thing and take it for a short drive and keep watch afterwards to see where it trickles from.

Here's a weird place to check...
1. Front backet holes on block (have had one block that was drilled through from factory and seeped out over time, mostly while sitting after being run). The oil ran all the way to the back of the exhaust under the car. That one took me a while to find.

Check
* Intake manifold ends?
*Oil pressure sender hole (on back of block)?
*Oil filter?

 

X2, but it's usually a lil messier than just a few drops. Still worth a look any how.

 

great ideas....I will give them a try

 

The place that i have found leaks the most is where the heads,block and manifold meet. I do like the powder idea. JW

 

This thread is like rolling a fat chick in flour.

 

I gotta tell ya, that powder trick might work, if you get the powder over the leak. Since you have only a general idea where its going to be a **** shoot or a huge powder fest.

If anyone ever powdered my engine to find a leak, first I'd laugh my *** off until I saw them shaking chicken feathers over it. Once the candles were lit I'd be scared.

However the UV die works on the premise of detection, only better and more accepted .