Welp, it's a concensus - I need to check and replace my freeze plugs - to be safe, am planning on replacing ALL of them.

Couple of questions regarding this - for the rear block plugs, is it easier to drop the tranny, or pull the engine, to get access to them? I'm not sure WHERE they are in relation to the rear of the block.

Also, other than the two usual in the rear, and 6 along the side, are there any other freeze plugs I need to look for?

I am planing to replace them with the brass plugs, to prevent this from ever happening again. Any suggestions on a good sealant to use for the new ones?

FYI, in either case, I plan to follow addidional advise for precautionary measures, to pull the pan and replace the oil pump, and rear main, just to be safe for several more miles down the road.

Final question, as someone HAS mentioned that perhaps the block is cracked - I have access to a good conection 3.9 from a 90 model.

Is there ANYTHING else I would need to swap the 3.9 V6 into my 91, other than the engine itself? Are there any differences in the wiring harness, motor mounts, ECU, etc, that I should be aware of?

 

I count 10 total freeze plugs. 3 on each side, 2 in front within the timing chain cover, and 2 in back within the bellhousing. If you dropped the tranny and pulled off the flex plate, the freeze plugs are right there, but I would say since you want to replace them all, pulling the engine would be easiest.

You really don't want to downgrade to a 3.9L. Especially after having the 5.2 in your truck. But, if your forced to go that route, you just need the wiring harness and ecu, the motor mounts are the same as yours.

 

The ones in the rear - are they easy enough to reach to remove th tap in, regarding the firewall? And the front ones - are the accessable without pullign the timing cover, etc? For the plugs on the sides, do I need to pull the starter, exhaust, etc to get to them, or are they somewhat easily accessible without such extensive disassembly?

Also, I do not have a book yet - have been spending all my available money of the parts and crap it needs - havent had the money to get a book yet... So, how difficult is it to remove the tranny? Can it be moved back enough to gain access, or fully dropped?

I would rather NOT downgrade to the V6 if I could help it, but it's a last resort plan, if i find the block is cracked.

 

I know you have a '91, which is pre-magnum, but we have in FAQ2 a link to download the '95 FSM. Parts of it will be different than yours, mostly engine related, but its a free factory service manual, so even with its differences, its proabably still better than a generic shop manual.

Now that you mention it, the firewall might make it hard to reach them, but not impossible. For the front ones, the timing cover does need to come off. For the sides, just go look at your truck and see how hard they are to reach.

 

And there is a 1990 wiring diagram in the FAQs.
I have the full 1990 service manual, however, I will only be in the country for the next week or so.

 

Ok, how difficult is it to pull the engine? I know the trans to engine bolts, and the motor mounts. Also, the fuel lines, and wiring connections - is there anything else I should look out for?

I am thinking about possibly just doing a basic re-ring and bearing job, while engine is out, also... According to the ODO, the engine only has 131k miles, for a 91, but due to the condition of the water, etc..., i'm guessing it's had some bad maint in the past....

 

I would say it's not hard, but I pulled mine out with the entire front clip gone, so nothing was in my way. But get a cherry picker and a friend and it shouldn't be too bad.

You'll have to remove the 2 engine-transmission brackets on either side, as well as the starter, and the flexplate bolts, and the bellhousing bolts. When you remove the flex plate bolts, push the flywheel back into the transmission to get it out of your way. You already mentioned the fuel lines (relieve the pressure before you disconnect it), and wiring harnesses. There are a few ground wires that will need to be unbolted. You'll also have to remove the manifold to y pipe bolts.

One warning though... don't bolt the hoist chains to anything aluminum, pick something a cast iron part just to be safe.

 

Right, no prob - won't be the first engine Ive pulled - it's just been a while...