Help with front crank seal on 1991 4.0 OHV

[jcook100]

Hi there,

I am replacing my old harmonic balancer and decided to replace the seal behind it while I have the thing torn apart. I am now ready to put the new seal in but have a few questions.

1. How far in do I need to push the new seal? The old one was recessed about 1/4" - 3/8" from the front edge (basically flush with the inner edge). Do I need to recess the new one to this same location, or can I just install it flush with the front of the cover then let the harmonic balancer "push" it to its final location?

2. The end of the cam shaft that is visible in the picture is not centered in the hole. Do I need a special tool to press the seal in, or can I just use a small ratchet extension with a mallet and slowly/gently tap it into place? I do not have a socket big enough to do the job. I am hoping I can just make it flush with the front edge then let the harmonic balancer push it the rest of the way.

Thanks!

 

[Shran]

1: It's not super critical, I'd probably put it close to where it was. The balancer will not push it into place, don't count on it doing that.

2: I have the timing cover removed every time I do this job. I would HIGHLY, highly recommend you do the same because your timing cover gasket is probably blown out or close if you haven't replaced it before. You are 90% of the way there already! Once it's off you can use a standard seal installer tool or piece of pipe or whatever.

Either way the balancer will not and should not be used to push the seal into place, it simply won't work that way.

 

[jcook100]

1: It's not super critical, I'd probably put it close to where it was. The balancer will not push it into place, don't count on it doing that.

2: I have the timing cover removed every time I do this job. I would HIGHLY, highly recommend you do the same because your timing cover gasket is probably blown out or close if you haven't replaced it before. You are 90% of the way there already! Once it's off you can use a standard seal installer tool or piece of pipe or whatever.

Either way the balancer will not and should not be used to push the seal into place, it simply won't work that way.

Thanks, Shran. This is very helpful. I do think those gaskets are leaking and would be good to replace, and the front crank seal will be much easier to replace with it out.

Question for you: is the bottom edge of the timing cover sitting on the oil pan gasket? I see some leaking from there too and am worried that I now need to change the oil pan gasket as well. Do you tend to do the oil pan gasket at the same time? This project has already ballooned in scope and I am worried to extend it any further (but will if I need to).

 

[Shran]

No prob.

Yes, the bottom edge of the timing cover sits on the oil pan gasket. Be very careful pulling the cover off and you will likely not have to replace the oil pan gasket, they rarely leak on 4.0s (usually something above it leaks.) It is almost impossible to change with the engine in the truck, so like I said, be careful But if you do damage it, you can use a big bead of RTV instead. I always use a little RTV in the corner where the timing cover gasket meets the oil pan on the sides.

Use a Ford timing cover gasket, WAY better than the Felpro junk. Part number FOTZ-6020-A

When you reinstall the cover, it's really easy to misalign the gasket... I thread all the bolts in a few turns, make damn sure the timing cover gasket is where it's supposed to be and then tighten all of the bottom bolts first to suck the cover down. Then you can tighten and torque the front ones.

 

[jcook100]

No prob.

Yes, the bottom edge of the timing cover sits on the oil pan gasket. Be very careful pulling the cover off and you will likely not have to replace the oil pan gasket, they rarely leak on 4.0s (usually something above it leaks.) It is almost impossible to change with the engine in the truck, so like I said, be careful But if you do damage it, you can use a big bead of RTV instead. I always use a little RTV in the corner where the timing cover gasket meets the oil pan on the sides.

Use a Ford timing cover gasket, WAY better than the Felpro junk. Part number FOTZ-6020-A

When you reinstall the cover, it's really easy to misalign the gasket... I thread all the bolts in a few turns, make damn sure the timing cover gasket is where it's supposed to be and then tighten all of the bottom bolts first to suck the cover down. Then you can tighten and torque the front ones.

I appreciate it. I already ordered the Fel-Pro gasket and it should be here tomorrow, but just ordered the Ford one from Amazon and am hoping it hurries .

That's a bummer about the oil pan. Is that unusual? I feel like most cars' oil pans are more accessible than that? Seems strange to me that you almost have to pull the engine.

Also, when you pull the timing cover, do you remove the alternator too, or can I leave it there?

 

[bobbywalter]

4.0 are a motha to deal with if you are used to working on inlines or 90 degree engines.

The way the oil pan is structured to the engine is the problem. You need a big lift and body lift...and it's not worth the headache. Just pull it....of course...that's relative situationally I guess.


Like he said ..for this job I pull the timing cover....many reasons for this...


I clean and right stuff the bottom ..and leave the cover looseish and slide the balancer on enough to engage the seal....settle the cover...snug a few bolts and pull the balancer....torque everything up and final and install. Had some issues with seal leaks just Poppin in a seal ....

But be careful ...some bolts corrode...and want to break

 

[jcook100]

4.0 are a motha to deal with if you are used to working on inlines or 90 degree engines.

The way the oil pan is structured to the engine is the problem. You need a big lift and body lift...and it's not worth the headache. Just pull it....of course...that's relative situationally I guess.


Like he said ..for this job I pull the timing cover....many reasons for this...


I clean and right stuff the bottom ..and leave the cover looseish and slide the balancer on enough to engage the seal....settle the cover...snug a few bolts and pull the balancer....torque everything up and final and install. Had some issues with seal leaks just Poppin in a seal ....

But be careful ...some bolts corrode...and want to break

Thanks!

Why do you slide the balancer on to engage the seal before snugging down the cover? Why not put the balancer on after the timing cover and water pump are back on and tightened down?

 

[bobbywalter]

Center the seal better when using rtv base.

 

[Shran]

There is an actual Ford tool for centering the cover, but good luck finding it. I also just slip the balancer on a bit, works fine.

I think I have always had the alternator and bracket removed for extra room to work. May need it off to see what you're dealing with.

The oil pan is what it is. It's bolted to the transmission as well... you maybe could get it out with the trans removed, I've never tried that on a 4.0. That does work on a 2.3, just barely have enough room to get it out. I doubt you want to pull your transmission at this point though.

 

[jcook100]

Thanks, guys. A couple more questions if it is alright:

1. Should I use RTV with the timing cover gasket? I know you said to use it in the corners (where the timing cover meets the oil pan) and perhaps on the oil pan surface as needed, but I mean around the whole edge of the timing cover too?
2. Should I use RTV on the water pump gasket surfaces in addition to the actual gasket?
3. Should I change the oil after doing this whole operation?

 

[Shran]

1: No, I always do them dry

2: You can... I usually don't. Just the gasket or just the RTV but not both. Sometimes I trust RTV more than gaskets, aftermarket gaskets are pretty crappy sometimes. The "good" 4.0 water pump gaskets have a bead of sealant molded into them as opposed to just a piece of paper.

3: Definitely! You will have at least some coolant in there, plus dirt & debris. I drain the oil prior to doing any of this...be careful not to knock chunks of crap into the pan while you remove and reinstall the timing cover. Some chunks will be inevitable, I spray a good amount of brake cleaner into the oil pan to flush out any crap before reinstalling the timing cover.