99 Head Gasket Project Update

[stickboy]

I am working on a 99 Limited 4x4 4.0 SOHC that I got from a friend for nearly nothing. Overall the vehicle is in pretty nice shape. Just needs some cleaning and a couple of little things fixed. While he still owned it, his thermostat went out and it overheated. After replacing the thermostat, there was still a lot of leakage around the front of the right head. Took it to a shop and they said it was a blown head gasket and quoted him in the area of 3k to fix. So he let me have it as a project car.

I finally got the motor torn out this weekend and started digging into the engine. After taking the right head off (and screwing up the timing...) I couldn't find anywhere on the head gasket where it looked blown. There was no water in oil, no steam in the exhaust, just a lot of water leaking outside.

You can see the stop leak, but it doesn't appear to penetrate the head gasket to the outside anywhere...

Upon turning the head over, I see this:

And finally, the thermostat housing where it bolts to the head. Note the shape of the O-ring. That is pretty much how I found it laying on the head.

So from initial examination it looks like I might still have a good head. Gonna take it to the machine shop to have them clean it, test it and check the valves. The rest of the engine so far looks really good. There is very little lip on top of the cylinders, and you can even still see some of the crosshatch from honing. Might need to see if this engine has had history...

Also, looked at the rear timing cassette and it looks really good. May not have to replace it.

 

[stickboy]

Can anyone tell if there are pieces actually missing from the thermostat housing? Is the hole only supposed to have that ridge only partway around? Maybe something broke away and caused the o-ring to blow out? Let me know what you guys think. Just didn't look right to me.

 

[rb142]

Looks like you got lucky with that leak. Your friend will be pissed.

Don't even think about putting that engine back together without replacing every single last bit of the timing components -- especially the rear ones.

 

[stickboy]

Rb142, Well noted on the timing components. I know I am going to HAVE to do the ones in front, so yeah might as well do them all.

I looked the head over really good and didn't see any cracks or other problems. I am still taking them to the shop to have them checked and probably resurfaced. On that note, should I have the block resurfaced as well?

 

[2000StreetRod]

stock thermostat housing

Below are photos of my stock thermostat housing compared to the metal I replaced it with.

 

[Torqueranger]

Below are photos of my stock thermostat housing compared to the metal I replaced it with.
View attachment 79055
View attachment 79056

Where did you get the metal one at and about how did it cost ???

 

[stickboy]

So looking at the stock one you posted, there are definitely chunks missing out of mine. Explains the leaking I guess!

Do you have a link to the metal one?

 

[2000StreetRod]

metal thermostat housing

metal thermostat housing soon available for v6 2005+ engine

It says for 2005+ but works with the 2nd generation SOHC V6 if you purchase the clip in sensors and clips.

 

[stickboy]

Got the timing cover off tonight and found some goodies in there. The primary chain tensioner was shattered and down to metal. I found plastic pieces from the primary chain guide wedged down between the oil pan and the balance shaft tensioner. That tensioner doesn't look all that good either.

Being that there are plastic parts in the crankcase, is it a good idea to remove both oil pans to clean out all of the chunks? I know it's a PITA to align when putting it back together and don't want to do it if I don't have to, but obviously I don't want pieces hanging out up there to work their way into the oil screen or something else. Thoughts and advice would be appreciated.

 

[2000StreetRod]

removing cradle

As I recall there were no pieces of my rear cassette guide in the block cradle. I reassembled the broken pieces to make sure I found all of the larger ones. My primary tensioner leaves were broken but the pieces stayed in position so I didn't have to worry about them getting disbursed. While I had the cradle off I removed one of the main bearing caps and checked for bearing wear. The bearing was in good shape considering the amount of sludge I found in the engine.

 

[koda2000]

re the metal thermostat housing, if you go that route (which i think is a good idea) i'm assuming the metal is aluminum, so be sure to put some anti-seize on the bolt threads as mixing steel bolts with aluminum causes electrolysis (i think that's the right word) to occur, which will make it very difficult to remove the bolts in the future.

 

[stickboy]

Probably a good idea regardless as the bolts are still threading into an aluminum head. Will keep that in mind.

 

[stickboy]

As I recall there were no pieces of my rear cassette guide in the block cradle. I reassembled the broken pieces to make sure I found all of the larger ones. My primary tensioner leaves were broken but the pieces stayed in position so I didn't have to worry about them getting disbursed. While I had the cradle off I removed one of the main bearing caps and checked for bearing wear. The bearing was in good shape considering the amount of sludge I found in the engine.

I only had a small piece of the primary leave left. I haven't taken the lower pan off yet to see what's down there, but I expect to find a few parts. Are there any gotchas to the cradle other than making sure it lines up with the back of the block? I watched a video where a guy took it off, but didn't show the process of replacing it.