oil leak from Back side of block

[spooln4fun]

Alright i have a oil leak i can't find..it has a new valve cover gasket on it, and was told it had a new rear main seal installed when they put a new clutch in it.....i have got under the car tightend up the oil pan, checked misc bolts and such under the car, andrechecked the valve cover.....leaks on the left side, the most(dr side), and noticed an oil drop off the laternator as well when under there today. Please help

 

[dr1665]

There's a number of sensors that screw into the backside of the block. If you're lucky, it's just one of them experiencing a worn out seal or something. Most common, however, is the head gasket. They tend to fail in that corner of the engine.

Some people might suggest pulling the valve cover, removing the head bolt back in that corner, cutting a thread or two off that bolt, and re-installing it due to a supposed factory machining inconsistency, but once you're leaking in that corner, it's a good idea to keep a close eye on you oil level (check it whenever you get gas) and start saving/reading up for a HG swap.

It's not as hard as it sounds. Basic tools and a weekend can do you right. There's just a number of other little things that have to come off to do the job that you might want to replace while you're at it.

Good luck.

 

[bullettdsm]

There's a number of sensors that screw into the backside of the block. If you're lucky, it's just one of them experiencing a worn out seal or something. Most common, however, is the head gasket. They tend to fail in that corner of the engine.
Good luck.

I'd give you some info, but Brian pretty much covered it

MB

 

[spartan]

Man, I am having that same problem on my 97 esi. I was hoping that I wouldn't have to do the headgasket because I really don't have the time or money to do so. How good of a fix is taking out that head bolt and trimming it? And can you fix that without removing the cams?

 

[VelocitàPaola]

And can you fix that without removing the cams?

Nope... it's impossible to remove any headbolt from the head without removing the camshafts. They can be loosened, but not removed.

Overall, it's a decent fix; but nothing works quite like a new set of ARP studs.

I'd check all sensors back there first, though. Especially check that oil pressure sending unit.

 

[DSMcrazy3]

So, what's being recommended is he remove a stock tty headbolt, modify it and re-install?

 

[xceler8]

Keep in mind too that if you are leaking from the head around where that bolt is, you might have both oil in your coolant, coolant in your oil, and your head gasket may be damaged. These are worse case scenarios of course. Probably the sensor.

 

[VelocitàPaola]

So, what's being recommended is he remove a stock tty headbolt, modify it and re-install?

No, it's being recommended that he be absolutely positive it's the headgasket that's leaking before doing any work.

 

[spartan]

And those signs would be... oil in coolant, coolant in oil, or low compression, correct?

 

[xceler8]

a good start. check your compression first. Your looking for a cylinder that's off from the others. ie..

180, 175, 185, 120

As long as all your cylinders are within about 15% or so from one another you should be fine. All age motors will carry a different compression, your looking for consistency amongst them. However, if they are all low, that could be a problem too.

 

[spooln4fun]

I will get back there and check the sensors as soon as its nice out...never pulled one out, i would assume its just an o-ring on there i can get at advance auto? also have never worked on a 420A, how ever changing a headgasket on a 4g63 is nothing new to me as have rebuilt a 1g awd.

Ok I got this from everyones wonderful input
1st check sensors, and there seals
1st B- check compression among all cylinders and make sure they are with in 15% of each other
2nd remove the corner head bolt trim off two threads (which side block side or head?)
if neither of those work
3rd Buy ARP head studs,and a new head gasket

Would replacing the HG on a 420 be similar to a 4g, just belts and pulleys are on the opposite side?

 

[xceler8]

Check my pm to you and let me know if you ahve any more q's after that.

 

[engineman100]

Alright i have a oil leak i can't find..it has a new valve cover gasket on it, and was told it had a new rear main seal installed when they put a new clutch in it.....i have got under the car tightend up the oil pan, checked misc bolts and such under the car, andrechecked the valve cover.....leaks on the left side, the most(dr side), and noticed an oil drop off the laternator as well when under there today. Please help

you mentioned oil leak after RMS and Clutch work, try removing the top bellhousing bolts and retorquing to the proper spec, i see a lot of shops install the bell bolts with an impact gun therefore warping the deck and then walla an oil leak.

 

[DSMcrazy3]

Even if that were what happened, retorquing to spec won't fix a warped surfaces seal; or lack there of.

 

[spooln4fun]

xceler8 I never recieved your PM, can you not just post it? or can try again though,but never got it

it is finally nice here for once been raining for like a week, so going to try and look again with the suggestions you all have commented about. Never thought about rechecking those bolts either. So hopefully i will find that leak today

 

[mountain_man]

i have the same problem...i replaced my head gasket AND valve cover thinking that it could be a warped valve cover. But it still was leaking. We eventually found the problem when we pulled the motor and it was some sensors that attached to the rear of the block. after inspecting the threading that mitsu did i can see why they leaked. The theading was visibly inconsistant and warped i don't even know how the sensors stayed in.

I am just saying that is what i have experienced. and yes i did fix the block.

 

[motomattxxx]

That would be the shoddy threading that CHRYSLER did, not Mitsu.

 

[mountain_man]

And yet again i am posting of freak'n threads that are older than me...GOSH IDIOT!!!

 

[spooln4fun]

Thanks for the input, really appreciate it....'

tightened all the bolts around the tranny incase that RMS was loose or warped, and looked on back side of block looks like one on DR. side may be leaking, how ever while under there observing and what not, noticed there was a drip of oil on bottom of alternator, along with a drip coming off pass side cv joint near tranny(know that doesont mean much as it turns alot) also some was coming off the back side of the brace that bolts to bottom of car, and front motor mount........BUt still hunting for this thing(trying break cleaner mether tomorrow)

 

[xceler8]

i have the same problem...i replaced my head gasket AND valve cover thinking that it could be a warped valve cover. But it still was leaking. We eventually found the problem when we pulled the motor and it was some sensors that attached to the rear of the block. after inspecting the threading that mitsu did i can see why they leaked. The theading was visibly inconsistant and warped i don't even know how the sensors stayed in.

I am just saying that is what i have experienced. and yes i did fix the block.

The factory oil pressure sensor is on the back of the block jsut below the head on the drivers side. Mine's leaking there too right now. My sloppiness after my rebuild. I'll repost my message, or just re-send it to you.

 

[spooln4fun]

alright, well put on new valve cover, and oil pan gasket, still leaking.

The sensors that are back on that side of the block near the firewall are what? I know oil pressure sending unit, and belive a knock sensor. Will I have to replace these sensors all together? Or are there just o-rings that are on the sensors for a seal? and also can i get to them with out pulling the motor, as in from the under side of the car and taking them out and replacing. Thanks for help so far everyone. Hope after i get these sensors replaced it stops leaking.

FYI have not noticed any oil in coolant or coolant in oil, have not check compression

 

[VelocitàPaola]

Will I have to replace these sensors all together? Or are there just o-rings that are on the sensors for a seal? and also can i get to them with out pulling the motor, as in from the under side of the car and taking them out and replacing.

The knock sensor won't leak oil if it fails.

You should be able to replace the oil pressure sending unit from under the car. It's a pain, but you can do it. Be sure to have the right socket on hand, and try removing the intake manifold bracket, cross-member or downpipe for easier access.

You should also be able to reach it from above if you know what to reach for.

 

[4UH8ERS]

The knock sensor won't leak oil if it fails.

You should be able to replace the oil pressure sending unit from under the car. It's a pain, but you can do it. Be sure to have the right socket on hand, and try removing the intake manifold bracket, cross-member or downpipe for easier access.

You should also be able to reach it from above if you know what to reach for.

OHH! and he also recommends that you put a healthy squirt of liquid teflon sealant on the threads of the new sensor or the old one when re-installing.

 

[eclipsers-t]

Try a lot of teflon before you go out and replace the sensor...even though it is just around 20 dollars or so....

 

[spooln4fun]

Alright, FOUND THE PROBLEM, took it to a local shop i trust alot, had them degrease it, and said is was leaking from the corner of the head gasket on the dr side. My question now is what sort of head gasket do i get, where to buy it, and where to get ARP studs. and a general idea what it may cost to have done by a shop