Front seal and carbon buildup - opinions


mazdab40004x4

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I've finally torn down the top end of my 4.0 to correct a problem with coolant dripping slightly into the cylinders and leaking all over the front of the engine. Didn't realize how bad it was -- still ran ok, but I could tell I had a vac leak from somewhere and could smell some coolant burning. Turns out the lower intake was literally loose on the block. I didn't even need a socket to get half the bolts out. I'm going to remove the heads to inspect and replace the gaskets at the very least. Possibly end up replacing the heads.

My first question is, if you were this far in, would you also pull the timing cover and replace the crank seal? I can't tell if it is leaking because the engine was so coated in sludge. Like literally two inches thick of mud and oil and coolant baked on. I cleaned the sludge but I can't run it in its current condition to tell if the seal is actively leaking under pressure. I'd hate to cause more problems than I solve but I would also hate to get it all back together and find a leak.

Also when I pulled the lower intake, the entire valley is evenly coated in a quarter inch of crusty carbon/oil buildup. Should I try to clean that up when I pull the heads? What can I use to do that so crap doesn't fall down into the cam holes? Or should I just leave it, get it back together, and run some seafoam through it?

Thanks for your thoughts.
 


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adsm08

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Lay rags in the bottom of the valley, clean it up as best you can, and use a shop vac to clean it up. Then run Motorcraft 10W-30 diesel oil for a while. It has extra detergents in it to keep the dirty diesel clean inside. That's the only real difference.
 

mazdab40004x4

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Thanks. What would you use to clean it off? Just brake cleaner and elbow grease, or something else? It seems to be crusty hard buildup more than slimy or sludgy.

I can definitely run the diesel oil.
 

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mazdab40004x4

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Thanks for the suggestion! I ordered those roloc discs and they are on their way to me now. I got a yellow and a white just in case. We'll see how it goes.

Any thoughts on the timing cover and front seal replacement? It's it a 'you might as well' or a 'stay away' job?
 

mazdab40004x4

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Well I got the heads off today and it's bad news. I have a crack between the valves in cylinder number 4 (front driver's side). So I guess it's time for new heads.

I am also noticing that the cylinder walls are very shiny. No scratches and no ridge at the top, but I'm not seeing any cross hatching. Just shiny metal. What can or should I do about this, if anything? I wasn't noticing any oil consumption or blue smoke before all of this but it could have been masked by the burning coolant.

The mileage on this engine is unknown but it's a lot -- north of 300k. The odometer hasn't worked from the day I bought it 10 years ago and the last known reading in the state system was 310k. I don't drive it much, maybe a few thousand miles a year so I'd guess around 350-400k total.

Any advice here would be appreciated.
 

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I'd start with a gasket scraper, then move to a razor for hardened deposits. Finally I'd use a rubber finger disc on a die grinder. This is the one I use:

https://www.amazon.com/Goodson-3M-Roloc-Bristle-Disc/dp/B0009RMAFM/ref=sr_1_4?ie=UTF8&qid=1548430424&sr=8-4&keywords=roloc+bristle+disc

They are a bit pricey, but they won't tear up the gasket surface, will polish it to a shine, and if you don't abuse them they last for a long time. The one I killed last fall I'd been using for 5 years.


I use the purple disks like that when I tear into an engine. I’ll spray penetrating fluid and go at it with a disk like that on a die grinder. Works quite well!


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Can you take a picture of the cylinder walls?

To me, I wouldn’t be throwing too much money at it with that high of mileage.

Post a picture to see how bad the cylinders are if you can though.


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I use the purple disks like that when I tear into an engine. I’ll spray penetrating fluid and go at it with a disk like that on a die grinder. Works quite well!


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Don't use the sanding ones like these on gasket surfaces:

https://www.amazon.com/DocaDisc-30PC-Conditioning-Stripping-Finishing/dp/B073D9WK9H/ref=pd_day0_hl_263_1/147-2607031-8712808?_encoding=UTF8&pd_rd_i=B073D9WK9H&pd_rd_r=18f83522-2292-11e9-b1bf-7d7bb058b622&pd_rd_w=iYFJ4&pd_rd_wg=76uYf&pf_rd_p=ad07871c-e646-4161-82c7-5ed0d4c85b07&pf_rd_r=JX27K2V45H7X3E16TNHR&psc=1&refRID=JX27K2V45H7X3E16TNHR

They can bugger the mating surface up and make it not seal well.
 

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Well aware. I’ve used those gently for exhaust manifolds and on the head if needed but like I said, very gently.


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Well I got the heads off today and it's bad news. I have a crack between the valves in cylinder number 4 (front driver's side). So I guess it's time for new heads.

I am also noticing that the cylinder walls are very shiny. No scratches and no ridge at the top, but I'm not seeing any cross hatching. Just shiny metal. What can or should I do about this, if anything? I wasn't noticing any oil consumption or blue smoke before all of this but it could have been masked by the burning coolant.

The mileage on this engine is unknown but it's a lot -- north of 300k. The odometer hasn't worked from the day I bought it 10 years ago and the last known reading in the state system was 310k. I don't drive it much, maybe a few thousand miles a year so I'd guess around 350-400k total.

Any advice here would be appreciated.
Feel for a ridge too. The ridge at the top is usually .020 inch or less. Enough to feel, not enough to see.

When I did my 4.0 a few years back I went whole hog and rebuilt it while it was out. The engine had 200K on it, but all the cylinders still mic'ed at factory new spec.
 

mazdab40004x4

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Let's see if this works. The pics from my phone aren't the best, but I think they show the shininess.







I did feel for a ridge and it's barely there if there is one at all.

Thanks all for your help.
 

mazdab40004x4

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Dang it. I guess TRS doesn't like Google photos. I'll try to figure it out when I get to my computer.
 

mazdab40004x4

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OK attempt #2. Let's see if photobucket works...

These are all from the passenger side of the block. I couldn't get a clear shot from the drivers side due to the tangle of wires, etc but it looks similar except the #4 piston is full of crud from the head being cracked.





 

mazdab40004x4

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Anyone have feedback on the state of my cylinder walls? I need to decide if I'm going to get new heads and put this back together as is, or if I need to do something more drastic. I'm not looking at engines every day so I don't exactly know what I'm looking at. I'd rather not do a full rebuild or buy a new engine, but I also don't want to put it all back together only to have it fail shortly after. It was running ok before the tear down with no oil consumption -- just burning and leaking coolant.
 


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