318 oil leak

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eightydeuce

eightydeuce

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I have an oil leak in my LA318. It is coming from behind the harmonic balancer and I'm assuming its the seal behind it? It's making a mess and leaving a small puddle of oil every it sits after driving. I bought the engine from some dude on Craigslist and other than this leak the engine has been fine. Is there any other spots back there that it could be leaking from? Any suggestions or tips on repairing this? I fairly new to this type of work and try to research as much as possible before I learn the hard way...although sometimes its unavoidable. Thanks


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From your description, I agree. Front seal for the Harmonic Balancer. It is pressed into the timing cover from the back. It appears some oil is being slinged upwards as well and then dripping down. This also aligns with this seal leak. Cheap fix but removal of front pulley and balancer,, brackets, water pump and timing cover is required.
If it was the front main seal, you would see oil coming from the rubber seal and running down oil pan. There would also be limited oil spray and just running down oil pan.
If you replace this crank seal , inspect the Harmonic balancer for wear where the seal rides. If there is a grove worn were the seal rides that must be soothed out.
Try this link for pictures.
https://www.vanning.com/threads/ubbthreads.php/topics/528275/re-318-front-crank-seal-question
 
Depending on the year of your 318 (or the year of your timing cover, anyway...) you would need to pull the whole front end off your motor to replace the seal (as Shig outlined above), but before you do that, just take the balancer off and inspect the seal area- early teeners had to be disassembled to replace the seal, but later motors (mid to late eighties? Not sure of exact year) went to a cover that installs the seal from the outside, meaning you don't have to do the whole disassembly thing- just something that takes a minute to check and could save you a bunch of time.
Old style:
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New style:
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Permatex Ultra Grey high strength RTV is your friend here. Like said before, get a front timing cover gasket kit Advance Auto Parts - Down for Maintenance, pull the balancer, water pump, and front cover. Make sure the seal surface is good. Trim the pan gaskets off flush with a razor blade. Coat both sides of your gasket surfaces with Ultra Grey, let it skim over, put the gaskets in place and seat in the cover. Seal your wet bolts with Ultra Gray (You can get anal and use high temp thread sealant, but I know commission mechanics use the Ultra Gray all the time for this with no comebacks). Leave everything loose. You want to install the balancer and let it center the cover in place with the seal before tightening the bolts down. This keeps the seal from being loaded to one side or the other and wearing itself or the seal surface of the balancer prematurely.
 
Thanks for the quick responses. I will just most likely just replace the balancer. Looking at rockauto and putting together a list of things to get. I think i need part number SKF 21944, it is listed as a "timing cover seal". I do not need the front crank seal correct? I know this is probably a dumb question so be nice. haha
 
Get a timing cover gasket set. Is your harmonic balancer actually bad? Your timing chain set, plastic top gear or steel?
If your engine has been apart, sure that it has, its probably a steel set, is the chain loose or tight? Your already in there, do it.
Pay attention to the length of the bolts , the lower right of the timing cover , it's short and goes into the water jacket, make sure you get that one right, a longer bolt will crack your block. There are only three bolts to put thread sealant on, the one that I just mentioned and the two lower of of the four long top bolts. Get teflon thread sealant, you can use silicone, but I wouldn't.
 
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I believe around 1977 the timing cover changed to where you can pop the seal and replace it without pulling the cover. I have 1 of each of these covers. I can eyeball it for the casting date but I believe its 77. I bet an early cover can be machined to a late style as i believe the seal is the same for both.
 
eightydeuce said:
I have an oil leak in my LA318. It is coming from behind the harmonic balancer and I'm assuming its the seal behind it? It's making a mess and leaving a small puddle of oil every it sits after driving. I bought the engine from some dude on Craigslist and other than this leak the engine has been fine. Is there any other spots back there that it could be leaking from? Any suggestions or tips on repairing this? I fairly new to this type of work and try to research as much as possible before I learn the hard way...although sometimes its unavoidable. Thanks


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A couple of things to pay attention to here.
Garrett’s last two sentences.
The only thing that centers the balancer in the seal is the balancer hub, so the timing cover needs to be loose as well as the oil pan.
It looks to me like someone might have tried to fix the leak already and failed because they didn’t loosen the oil pan.
(Maybe/maybe not)
Some can do this without loosening the pan, but it takes experience to pull it off without causing the same problem.
BTW the front crank seal IS the balancer seal.
 
Forget it, I got it off. It has a nasty groove in it.
I got the older style timing chain cover too.
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Can't imagine someone putting that back on. I guess that you could try just putting a new balancer on, if it leaks, you will have to pull the cover anyway. This does make me wonder what else they did wrong. Make sure that your new balancer is for a internally balanced engine.
 
A new OEM balancer is only about $95. Just got one for my 318, the rubber elastomer was degraded from years of oil.
 
Yeah there"s no way that is getting buffed out. I dealt with the same issues on my divorced transfer case and I wound up just replacing all the yokes and seals. The easy route would be the sleeve and just give that a shot, but like Cruze said. what else could be wrong??? I didn't pay a lot for the motor so I can't really complain. I'm probably going to just tear it all apart and replace timing set too. Any recommendations on timing set? The engine is in a Kaiser Jeep M715 and it is mostly a grocery getter and cruise around truck.
 
See what shape the chain is in. If it's got an aluminum/nylon cam gear replace it anyway. I would go with a double roller chain myself. Make sure there's an oil slinger in there.
 
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There is a timing chain tensioner listed on Summit that’s about 35 bucks. We have been seeing a lot of chain stretch lately from name brand chains and rebuilds with less than 10 hours. @lead69 swares by the Summit Chain...
 
Being that is in an M715, I would imagine there's plenty of room to drop the pan and replace those gaskets, too, isn't there? TrailBeast is correct, that front cover is difficult at best to put in with the pan fully bolted in place.
 
I decided to disassemble everything instead of just sleeving the balancer and hoping for the best. I got a new balancer, timing chain set, Advance Auto Parts - Down for Maintenance Felpro gasket set, oil pan gasket set, Permatex Ultra Grey, Teflon thread sealant, and I plan on adding a chain tensioner. Is there anything that I'm missing or might need?
 
I would skip the tensioner if you got a true roller timing chain.
 
CRUZE 418 said:
I would skip the tensioner if you got a true roller timing chain.
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I’m about to pull my 340 out after about 25 hours for a head swap that @yellowrose did the porting job on along with a cam. We were having some timing issues, at 3k rpm all in at 36* we were getting about 8* retard bouncing a around in the light. We tested the MSD box and dizzy and that came back with no issues. So I bet that the Cloyes double true roller timing chain is stretched and causing timing issues...
 
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The tensioners are not compatible with some roller chains, check first. Make sure slinger is there and facing the correct direction.
Download a service manual and follow the directions for the timing components installation.
Service Manuals – MyMopar
 
Thanks for the help everyone. I have everything disassembled and there was no slinger in there. I ordered one and will wait for it to arrive before I reassemble everything.
 
Does the top left bolt in the cam retainer plate have a hole drilled through the center?
 
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