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Oil leak


mom'sZ

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I have a mostly stock L-6 in a 77 280z. Last time the engine was out I replaced the valve cover gasket, it was leaking pretty bad. The car still has an oil leak. It's a fairly high mileage motor. I thought it might be the oil pan gasket or the rear main seal. I jacked the car up and crawled under to look and it appears to be more coming from the passenger side of the motor. It doesn't seem to be coming from the valve cover gasket anymore, it looks more like it's coming from the head gasket. ? This seems odd to me and I wondered if anybody else ever had this or is it common. The other possiblity is the oil pressure gauge sending unit. It is stock and original (30 years old) and doesn't work. The oil around the head gasket could be radiating up from the sending unit. It's only in that area. Anybody had any experience with that?

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*edit* 81280zx beat me to it... Ditto everythign he said...*

 

 

With all the possible points of oil leaks you mentioned, you really need to start hunt for leaking oil, from scratch. If you don’t start from scratch, you are just wasting your time on a wild goose, er, oil leak chase that you most likely wont find the “actual” leak location of. Trust me, been there done that MANY times… wall.gif

 

What I mean by starting form scratch is, using engine degreaser, completely clean the engine block, cylinder head, valve cover, front cover, crank damper, oil pan, and around the entire circumference of the tranny bell housing and remove ALL the grit and grime, wet oil etc. Depending on how grimy the engine is, this could easily take 4-8 cans of FOAMY gunk. (I prefer the FOAMY Gunk over the regular Gunk, if you have something you like better, then by al means use it), and a nice stiff bristle brush and running water.

 

Once you get everything cleaned and all gasket areas such as the valve cover, front cover, head gasket, etc are all clean of any previous oil residue, then drive the car on a short jaunt, and when you get it back home, let it sit for an hour or so, then open the hood and give all those areas a good visual inspection. Start low, under the car, front and rear of oil pan, tranny bell housing, and when you find fresh wet oil, then follow that wet oil trail UP the engine to its highest point of wetness. That should be the location where the leak is coming from. If you see more than one trail of oil, track those as well.

 

OH! Don’t forget to eh cover the distributor with plastic baggy and use rubber band to keep excess water spray from getting IN the dizzy. and after you thoroughly clean the engine, don’t forget to unplug the TPS connector and make sure there is NO water in the switch connector. If so, just blow it out till it is dry, then reconnect he TPS connector. mannagg.gif

 

Tools…

 

Cleaning.jpg

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Thanks for the tips on engine cleaning guys, but like I said, the engine was out last summer and I wouldn't go so far as to say it's spotless under the hood (it's driven almost daily) but it is pretty damn clean under there. I did take a leftover half can of gunk and blasted that side of the engine. Took the car for a ride and it seemed to definitly be coming from the oil pressure sending unit. Looks like it comes out the end where the wire plugs up. Anyhow, anybody ever seen this? I have some BSP plugs and the dog gone thing never worked to start with, so I removed it and put a plug in it's place. I have aftermarket gauges I'm going to install.

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I just had a really bad oil leak and if it wasnt for "Flourescent dye" i would have kept looking in the wrong places.

Steps: clean motor, add dye, let car run until fully warm, turn off lights...Turn on blacklight, watch the dye come out

IMO this stuff is the best way to go...Its easy

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I just had a really bad oil leak and if it wasnt for "Flourescent dye" i would have kept looking in the wrong places.

Steps: clean motor, add dye, let car run until fully warm, turn off lights...Turn on blacklight, watch the dye come out

IMO this stuff is the best way to go...Its easy

 

agreed, this is the fast track route to tracing a oil leak issue.

 

though having a clean motor prior to appliciation of the die is useful too.

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Well, the oil pressure sending unit it was. Stuck the BSP pipe plug in it's place and the thing is as dry as a popcorn fart. I have two spares (on spare motors, not new) I wonder what the chances of either of them not leaking and also working would be. I hear they are notorious for not working.

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