91LS400vgb

I have a 91 LS and I recently changed the valve covers as they were leaking. I followed the installation steps carefully using the lexls tutorial as a guide, and I applied FIPG to the 8 indicated area and it all looks good, except now it appears that oil is seeping from the front right cam bearing cap, which is just ahead of the valve cover. What's worse is that its dripping down and getting on the alternator (the power steering fluid is not leaking - it's definitely engine oil coming from the cam area). I checked the service manual and it appears that the cap is sealed with FIPG. It looks like I need to remove the valve cover again to remove this cap and reseal it. My only concern is that I believe when the cam is installed, the bolts for all of the bearing caps are supposed to be tightened in a sequence, so will it be a problem if I just remove and replace the front cam bearing cap without disturbing the other bearing caps? Has anyone repaired a leak on one of these before? Thanks in advance.

dicer

Removing a front cap with tension on the belt shouldn't hurt a thing. I'd be more worried about the seal.

91LS400vgb

Good point, dicer. The front cam seal is a definite concern because I don't want this to turn into a timing belt job. I'd be very interested to know if someone here has been able to fix this leak without causing other issues.

Banshee365

Yes, you can remove the front bearing cap and reinstall without any problems at all. I've done it on the 1UZ and many other engines. Although, I somewhat doubt that much of an oil leak is all of a sudden dripping out of the bearing cap mating surface. They say to place a VERY VERY thing layer of FIPG on certain spots of the bearing cap but the truth is that those surfaces are very well machined and even without sealing I would imagine a leak from there would be every so slow. If the leak just showed up I'm betting your leaking at the corner of one of the bearing caps where you put the sealant for the valve cover gasket. You have to be very careful when dropping the valve cover back down as you can kick the sealant from the areas they need to be in off to the side very easily. Did you remove, clean, and reseal your semi-circular plugs as well?

The bottom line is that if you did not have this leak before, but now you suspect the leak from the cam cap AFTER you did the valve cover gasket job then I can almost guarantee you the cam cap is not your problem. But go ahead and remove it and reseal while you're there. No harm in doing that. Now, when you apply the sealant to the bearing cap surface it needs to be nearly see through. If it's an even black coat that is too much. There is an oil channel that separates the two machined surfaces on each side. You place sealant on the surfaces outside of that channel. The channel lubricates the seal and aids in bearing lubrication up there. If you put too much sealant you will plug that channel and create new problems. The film needs to be very light. Obviously torque the bear cap bolts to the proper factory spec.

If I were you, I would do something you may think is crazy. I couldn't bring myself to go through all that work and not change the cam seal. I would personally go a little deeper to accomplish this. I would probably remove the no.2 timing cover and distributer housing/cam position sensor on that bank to fully access the cam sprocket. Then I would mark the timing belt to the pass side cam gear just in case. Then remove the hydraulic tensioner on the bottom of the engine. You could jam some towels or something with some firmness against timing covers and the timing belt to avoid skipping teeth but the belt is pretty tight even with the tensioner removed. At this point you could put the open end wrench on the flats cast into the cam and remove the cam sprocket nut. I would probably bungy the cam sprocket with the belt still wrapped around it to the hood or something holding it slightly out of the way. Then you can remove the black metal cover behind the cam sprocket to reveal the cam seal. The cam seal is much easier replaced with the bearing cap off. You don't have to mess with running a screw into the seal or anything. It just pops right out with the bear cap off. Then you can also install the new seal with the cap off but ensure the seal is flush with the front of the head afterwards. I usually partially install then tap it the few mm's to go after that. The cam sprocket is keyed with a pin and only goes on one way. You could check timing afterwards but if you are even the slightest bit careful I think skipping a tooth on the belt doing something like this would be difficult. Just don't let the belt get much slack. I would skip on the right cam before the crank. The belt wraps tight around the crank without much clearance so it stays pretty well.

91LS400vgb

I'm glad to hear that you've done this many times. Originally, my valve covers were leaking, but I can't be sure if oil was previously leaking from the bearing cap area as well. I purchased an endoscope to search for my current leak and it does seem that oil is leaking from bearing cap mating surface, though it's hard to be 100% certain. I did not reseal the semi-circular plugs, though they seem to be dry. I will do that next time. Thanks for the tips on keeping the oil channel in the cam journal open - plugging that would be a costly mistake.

I'm intrigued by the idea of changing the cam seal using the method you describe. That would save a lot of time and it is very tempting to do while I'm there. Thanks for detailing the steps - it makes a lot of sense.

TDIGREEN1

Just FWIW - on my '93 I chased this leak for a couple years thinking first it was the PS pump and then a cam cover gasket - and it did eventually ruin the alternator. Found it was that bearing cap during gasket replacement. Did remove and apply thin coat of FIPG sealer and it stopped. The following year the other side started leaking - sealed that one too. All good. So, they do leak. But the mating surface is very narrow between the oil gallery and the edge of the cap so be sure to use a very thin coat of sealer. Never did have an oil leak on the ps pump but did the fix anyway.
Now if I could only repair the condenser cooling fan circuit....

91LS400vgb

Yeah, my driver's side bearing cap is also leaking now too. I sealed the passenger side bearing cap with a very thin coat of fipg since it was dripping on the alternator. In my case, the oil actually soaked the brushes causing them to wear out quickly, causing the alternator to fail. Luckily I was close to home when it happened.