New to forum

[Keno1]

Hello, I just purchased a new to me ranger. 2000 ex cab 4wd with a 4.0 and 280,000 miles. Everything works great, but no compression on one cylinder (air blows right out exhaust pipe) and 90 comp in another (exhaust pushrod never loosens up and rocker arm sits higher than the other two next to it) . Looks like I have two bad exhaust valves. I'm getting ready to pull engine and replace heads with remanufactured heads.
I'm looking for advice on what else I should do while engine is out, and any other top end parts I should replace while replacing heads.

I'm glad to be a member here since it looks like there is amazing collection of knowledge on this forum.

 

[franklin2]

280,000 I would check everything in the engine. Pull the heads and then turn it over and pull the pan. Pull some of the bearing caps and see what they look like.

Find a good machine shop in your area that will work with you. Take the block to them, they will measure it and tell you if it needs bored. Generally, if it's worn more than .006 it needs bored. This is where the cost goes up because after the re-bore, you will need oversize pistons.

Take the crankshaft also. They can measure that too and tell you if it needs to be turned. They can turn it and you can run undersized bearings.

And get a full engine gasket kit, and replace all the gaskets. Timing chain and gears unless they look new from being replaced before.

Just go through the whole thing. 280,000 is a lot of miles for any type of engine.

 

[Keno1]

That's the info I was looking for. Thanks. Engine is out now. Cylinders look great. In fact each cylinder still shows the crossing marks from the honing. Unless this would normally show on an engine this well used, it's possibly a new short block? All exhaust seats are significantly sunken into the head.

 

[franklin2]

Take the heads to your machine shop, or shop around for a machine of your choice. They will look at them and see if they are repairable. Once in awhile the valves are sunk in so far that they have to replace the valve seats. This is a lot of work and a lot of labor (money). So if they come back with a big price, then you can shop around online and see if you can find something cheaper. You can also carry the block and the crank to them and they can measure and verify that the cylinders are really good, and check the crankshaft also.

You will need to check the crankshaft surface at the rear main seal. A engine with this many miles can get a groove worn in the surface where the seal runs. They make repair sleeves you can slip over the crank to get rid of the groove.

The same thing happens on the front crankshaft damper. It may have a goove from the timing cover seal. They make a repair sleeve for that one also. If your damper has a rubber ring made into it, make sure it's in good shape and the rubber is not falling apart.

 

[gaz]

@Keno1
You have options for the top end:
1) perform a "Parade Rest" teardown of the valve train, determine the survivability of the push rods a rocker, if they are good, use them.
2) a) replacement push rods are over the counter, however, if after the rebuild your dimensions ∆, then Smith Brothers offer custom length, both adjustable and solid push rods.
2) b) Delta Cam of Tacoma Washington offers the only improved rockers available; they have gardened inserts.
3) it is a non adjustable valve train so the adjustable push rods, for a few dollars more are a SUPER value.
4) another option is to have a set of Ford 2.9l adjustable rockers machined fir use in the OHV 4.0l. It is reasonably simple, 6 of them need to be milled something like 1mm (I forget the actual measurement ).
5) after the rocker arms are thoroughly cleaned, drill the oil passages 1 Machinist's drill bit size larger (rockers too), put a bevell on the cut surfaces and buff. This will result in improved top end oiling.
6) the springs on the rocker arms can be replaced with spacers; this will permit the rockers to move freely, resulting in very slick sliding top end components.

As @franklin2 mentioned, depending on the condition of those heads/valve seats, they may need to be reground (if your lucky), can be part of a performance valve job ..)

I hope that your heads are OK, If have two sets of good, serviceable used 4.0 heads so far, so they exist

On our information page there is a hyperlink to Sven Pruett's "How to Build and make Power with the Ford 60°V6". It is ABSOLUTELY worth reading! It covers everything that I've mentioned and much more.

PS, if those cylinders have cross hatching, you have one answer.
-The over size of the piston is marked in the center on top.
-the reason for the low compression cylinder should rear it's ugly head soon.

 

[Keno1]

Low compression was exhaust valve seats. Pretty much gone. Also each head was cracked between valves in one cylinder. New heads from King cylinder heads and the new rocker arms solved the problem. We took the engine out. Everything on bottom end looked good. Probably a remanned short block? Replaced all sorts of stuff (clutch and slave, rear main, oil pump) cleaned it up and slapped it back in. Forgot to hook up the big hose right under the throttle body. But once we figured out what we forgot we now have it running like a champ. Thanks for the help.

 

[franklin2]

Not sure if the Germans put extra goodies in the blocks on these 2.9's, but I have one that has a lot of miles, and the lower end looks great. If Ford hadn't got a hold of the heads and thinned them out, this engine would most likely be one of the reliable legends. It's my understanding the european heads don't crack like the ones over here.