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My 740 was dripping for a while but now I see a trail of drops. I checked the oil and filled it up , maybe a tad too much , Ill check that. but I know it's been leaking and it was down a whole quart, usually I Haven't needed to add oil between changes. I think its dripping so bad now that I'm loosing so much that I need to fix it. I dont really want ot tow it to a shop to drop a thousand bucks on this issue, The costs are a concern.
Ive seen leaks in my 240 caused by a leaky oil separator box and I have also heard of them cracking. I might have a pan gasket issue but I'm kind of thinking it's the rear main oil seal.
can I suspect the drip will be more from under the bellhousing than the pan if it's the rear main oil seal?
I thought of wiring a catch tray with a diaper in it under the bellhousing so I can drive it without a trail of oil following me but maybe it could suddenly get much worse.
. I took it off the road for now. It looks like I might need to pull the transmission or the engine. I dont have a lift or a garage to work in. Im dreading pulling the transmission to fix it but that may be what's needed. I dont own an engine lift, could rent one.
If it ever stops raining I'll put some paper under the car and let it run to see if I can see where it's dripping. If I'm pulling the trans Ill also do the output shaft seal.
Ive pulled engines out of automatics and Ive done clutch replacements requiring the manual trans be pulled. I know it can be a bit of a hassle to get things aligned with just blocks of wood on a rolling type of car jack and no transmission jack but it's possible. Im trying to determine if Ill have a lot of issues with that with this auto transmission. In particular the alignment and insertion. with the manuals I've made up a plastic alignment tool to help align the clutch but this does not have a clutch so maybe that tool is not necessary with an automatic?
I assume I might be best to drain the trans and the torque convertor before removing it, is draining the torque convertor necessary? I remember pulling a trans from a 140 and was a bit suprised when the torque convertor came off along with a huge dump of trans fluid from behind it.
Im wondering if maybe I can get a nearby shop to do the trans pulling and maybe take everything else off like the driveshaft and most of the bolts and linkage then having it towed in to do only the trans pull and replace. I dont really want to crawl in the dirt doing this but I can probably do it.. maybe that would only take a couple of hours of shop time that way and a shop could then help with the actual transmission pulling and replacement which is the hard part.
Ill check the pan bolts and the oil separator and clean the flame trap first, If I do find loose bolts then that might be a good thing but I'm suspecting the worst. I think a pan gasket failure might cause a drip but probably not a constant drip. Ive yet to determine if it leaks when not running but I think it is not leaking so much when parked, just lots under driving conditions.
Phil
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If you're losing a lot of oil then there should be good evidence on the engine. I'm sure you know most of the usual places, so consider this checklist a reminder.
Excessive crankcase pressure is often behind oil leaks at weak points like oil seals (or worse still pushing them out, often the case when there is significant oil loss), so always start there.
a) Check and clean your PCV system, flame trap element, small hose to throttle body (incl nipples both ends and the tiny holes in the throttle body throat, also a good excuse to remove and thoroughly clean the TB ).
b) Check for a plugged oil separator (remove the oil filler cap and try blowing back into it through suitable vinyl tubing). A badly dried out O-ring at the base is a less common source of leaks, but if you've had the oil box out and didn't replace the O-ring or properly tighten it then a distinct possibility.
c) Check around the valve cover, especially the front edge.
d) Check for leaking front oil seals, either worn or pushed out from crankcase pressure. Check for evidence of oil at the bottom of the lower timing cover. It's often grungy there anyway, so if it's not fresh oil then wipe clean and recheck after some driving. If you need an excuse to replace the timing belt then this is it so you can remove the timing belt covers for a full inspection and seal replacement. If the seals haven't been done in living memory then replace them all.
e) Check the back of the block for oil leaking out under the distributor. If suspected there then check inside the distributor cap. Worn O-rings and the distributor shaft bushing can leak oil down the back that can make you think it's the rear main seal.
f) Check under the oil filter in case it's not properly sealed or a wire accidentally got pinched behind the seal at the last filter change.
g) Saving this for last in bad weather, you need to crawl underneath and see if it's the oil pan, drain plug and yes, the rear main seal with excessive oil coming out from the bell housing. If you don't see fresh oil then clean off all the grunge and see if it comes back. If it is the main seal and because it's such a hassle to replace then as long as it's not pushed out, cleaning the PCV system can often slow the leak to a tolerable level (often my case).
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Dave -still with 940's, prev 740/240/140/120 You'd think I'd have learned by now
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Additionally, if you suspect leaking worn seals (especially the rear main seal) then use 'high mileage' motor oil that contains seal conditioners and/or use a seal conditioner additive. Switching from dyno oil to synthetic can also exacerbate seals leaking as the engine deposits that are soon dissolved were in fact contributing to the seal. I stay with a high quality dyno oil for just such reasons on my high mileage engines, changing it more frequently what with the cost savings.
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Dave -still with 940's, prev 740/240/140/120 You'd think I'd have learned by now
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thank You dave, lots of good info there . I was not aware of the idea of blowing in through the oil filler cap to detect a leak.
Ive done the belts and front oil seals on this engine before.
Ill check if the flame trap which looks like a plastic plug full of 1 mm or so holes and is located wehre there is very little room for hands under the intake manifold. If I find that plugged with balck goop it might tell me the story.
yes Ill clean the pan area. I had a flame trap come loose on my 240 ( same engine) it looed like an oil pan leak.
I have a feeling that if it's the pan I'd see sort of a slow drip but maybe not such oil loss so Im fearing it's the rear main oil seal. I of course want to determine this is the case before I go pulling out the transmission.
I usually use 10W 30 regular oil not synthetic. maybe 20W 50 is ok since its a bit older.
I previously had issues with a stuck injector adding about a teacup full of raw gas into cyl 3 upon each shutdown. It took me while to find and solve, so maybe the oil had some gasoline that worked past the pistons and it may be polluted , that might be bad for the seals too.
Ive never tried the seal swell stuff , I'm not sure how much faith to put into that but is there type or brand that you think might help?
the rear main seal rides on the crankshaft. I thought I might be able to reposition it laterally, just slightly, if the crank is worn there where the seal makes contact.
I have another similar 740 that I bought for parts and drove home, it have very little maintenance and was pushing the dipstick out, and some oil, so I think that one has a serious case the plugged flame trap issue.
I assume if you remove the oil filler cap it should have suction.. would it then blow if the crankcase is going high in pressure? im trying to think if there is any airpath between the rocker cover area and the sump or if these are two different "containers"
Im trying to think how the apparent pressure in the "rocker box" can be used as an indication of engine wear or other issues.
the compression is 150 or so on all cyls..
It seemed much worse after the oil light popped on for a sec when cornering and I found it down to the line and added oil. maybe it would leak less if it's down 1/2 a quart?
If it's the pan gasket I think it's not full up to the mating line so in that case it would only leak there at least any considerable amount when the oil can slosh. I dont think a leaky pan gasket can cause a constant drip when not being run. Ill check all the bolts and the oil separator bolts and make sure the flame trap is cleared as a first step.. . I had a leak in my 240 and it was only a loose oil separator.. It looked like a pan gasket leak.
the top half of my engine and around the timing belt and distributor is clean.
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Sorry, I meant blow into the oil separator, not the oil filler. You need to open the filler cap to let air escape. That's to check if it's totally plugged. If the oil separator is marginally plugged and you're suspicious then you may want to remove it for closer inspection and attempt a cleaning.
The suck down test at the oil filler doesn't seem to work as well with the newer engines for some reason. You used to just loosen the cap to see if it rattled. Now you need to cover the opening with something like wax paper or plastic cling wrap to notice any suction. I no longer bother, but I do check my flame trap regularly. The flame trap is easier to see and get at with the TB removed, also of course accessing the oil separator box. If you've got an EGR valve mounted in front of the box and blocking access then getting that out if the way can be a real pain and if you're not careful may split the tube routed around the back of the engine, a part that is reportedly unavailable. I remove the TB anyway for a thorough cleaning and inspection at every oil change anyway so it's easy to reach underneath the manifold to restrain or reseat the flame trap hose on the oil separator. If you do it regularly the flame trap and PCV hoses don't get welded in place. The small plastic nipple on the flame trap housing gets brittle and is easily broken if you're not extra careful..
For seal conditioners in the oil, I wouldn't use them on newer gaskets as tge softened seal wears faster, but I'm willing to change the front seals more often if it extends the life of a worn rear main seal. As for repositions the rear seal on a less worn section of the crankshaft, if you can set it slightly deeper rather than shallower. There should be a lip at the back to prevent pushing it through. As for brand of seal conditioner, I forget which one I've used, perhaps Lucas, but any reputable brand should do.
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Dave -still with 940's, prev 740/240/140/120 You'd think I'd have learned by now
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