I posted this on the ford explorer forum but realized this is probably the best place to ask this question.

A friend gave me their truck after it's been sitting for a year. I did some inspection on it and it looked ok. It started right up so I shut it down immediately. Then I started inspecting the fluids and found the coolant had leaked into the oil and had been completely emulsified into a nice latte.

I drained all this out (an impressive 4 gallons so I suspect they kept adding water) and flushed it a bit and removed all the coolant. I ran it for a few seconds at a time just to flush some of the water out.

I pulled it all apart and found 3 cylinders were leaking badly into the coolant. I had a machine shop check and plane the heads and reseat the valves and stem seals. After thorough and careful cleaning of everything it all looked ok and went back together nicely. I followed the manual and did the 4 step torque method and torqued everything else back down.

However when I went to turn it over it seemed to just spin without resistance like the valves were stuck open. I put a compression gauge on all the cylinders and found they didn't even move the needle. Right now there's no coolant in it, because I wanted to take it one step at a time.

I'm not sure what could have gone wrong at this point. I did verify there's fuel getting there and spark, just no compression at all. Since this isn't an overhead cam, I'm not sure how the timing could have been disturbed. I've never seen this before and I'm at a bit of a loss of what to do.

Anyone have some ideas?

Thanks

 

Welcome to the forum

Reads like valves are not closing all the way
Pull the valve cover on one side and see

 

I ordered a leak down tester, so I'm going to strip some stuff back off the engine. But when I was putting the rocker arms back in and the lifting rods I was very careful to visually inspect the lifters were seated right. And only a few compressed the valves open like you'd expect depending on the cycle. Is there something more I could do to find where all the pressure is going without the tester?

 

Yes, when you put air into the spark plug hole(leak down tester), when that cylinder is at TDC Compression stroke, listen at the tail pipe and intake to hear where the air is leaking

It will be coming from either the exhaust valve or intake valve

One thought, if there was that much coolant leaking into a cylinder there could have been a hydro-lock, and that could cause crank's timing gear woodruf key to shear off or cam's key, this would throw off valve timing
Easy to check for this with either valve cover off, #1 and #5 are both at TDC with timing mark at 0, one is at the end of compression stroke the other at end of exhaust stroke
So manually rotate engine to make sure valves are in time with crank

 

Thanks for the help Ron. I'll check that out too. I suspected something like that could have happened, but I drained it all out and briefly fired it up 2 or 3 times for 2-3 seconds each to try to purge out any residual foam/oil. With that fluid out it still would still fire up fine. However something is obviously very wrong now.

 

It does sound like you have valves open all the time if you are not getting the needle to move at all.

 

If the truck has been sitting for a year with all that milky oil in it, then I would suspect the internal workings of the lifters to be stuck and not allowing the valves to close.

 

Here's a little more background after I did a leak down test. The truck was running just 2 months ago and it sounded smooth. I did run it without coolant (due to the leakage) and I only ran it for a few seconds at a time to assess any additional issues. After this point it sat for the 2 months with some fresh oil in it to try to keep it protected some.

Since it ran ok, I decided to tear it down and see what I could find. The head gaskets were shot for 3 cylinders an maybe more. So I had the heads planed, valves reseated with new stem seals and this is when I made this first post a few weeks ago because I was getting 0 psi compression after putting it back together and the engine was spinning. Now I have a leak down tester so I'm starting again.

Today I removed the exhaust and intake manifolds and took off the valve covers. While cranking I could see the lifters rising and falling around the cylinders. Visually it looked ok. I took off all the rockers and lifters and pulled the spark plugs. Then I checked each cylinder.

#1 - 11% leak
#2 - 13% leak
#3 - 10% leak
#4 - 14% leak
#5 - 14% leak
#6 - 15% leak - this leak was into the intake manifold

1-5 seemed to be leaking into the lower body past the rings. I didn't rotate the engine to top dead center, but I did remove the rockers so the valves should have been closed. I know this might not be quite the right technique but I'm just doing some debugging.

First off I can hear the leakage and it sounds bad, but the gauge says <%15 and stays in the green. When I disconnect it, there's definitely some pressure that quickly escapes too so it's holding something.

However when I crank the engine it just sounds like it is free spinning with not much kick or shudder and in the past the compression gauge was showing close to 0 psi.

I've never done this type of debugging before, so I'm open to any ideas. I did turn the engine over with the rocker arms off just to see if pressure would build up and it seemed to build some and the rotation felt different and slower.

 

With no valves there is no way for air to get in so....................no compression of the air, except whats already in there, and most of it will leak out past the rings.....AS IT SHOULD.

Metal on metal rings/cylinder walls, and valves and valve seats are NOT air tight, and not suppose to be, they temporarily hold enough compression for engine to start cold, and then temporarily hold the 900+ PSI of a cylinder firing so that it pushes down on the piston adding power to the crank shaft

Leak down only works with that cylinder's piston at TDC, you can retest that if you want but if you heard a leak from intake port then that head needs to be pulled, and that means the other head as well

 

Have you done this yet ?

 

Ok thanks. I've never done this test before so I wasn't sure how to interpret the results. I didn't realize that they would leak normally. When that started to happen I decided to stop and see what you guys thought. I'm not sure why #6 is leaking out the intake but I went ahead and just checked all the cylinders to see what happened.

I'm not very familiar with this engine either. Tomorrow I'll rotate it and check TDC leak downs and I'll go through and check that #1 and #5 are at the right setting too. Then I'll go from there and see what's going on with #6 as well.

I'm just curious why would I need to pull both heads if one side seems ok? I don't have a problem with pulling them, but I've had them out twice and to the machinist already. I was hoping to avoid going back through the torque process for both of them.

 

The timing appears correct to the best of my knowledge. I rotated the crank to TDC mark and felt the #1 air getting pushed out with both lifters down (valves closed) and it peaked around TDC markings. Cylinder #5 has a wide open exhaust valve. I assume that is correct because it is expelling. Is that right or should #5 lifters both be down?

I read through the Haynes manual again on it and it's a bit vague in places, but I think I'm doing it correctly.

Also the one cylinder that appeared to have a leak on the intake side seems ok now. I don't know if it just didn't seat right or something, but I'm unable to repeat that problem.

 

Yes that would be correct for TDC #1
#5 exhaust valve should be closing though as #1 approaches TDC, then #5 intake valve would start to open just after #1 TDC

 

That appears what's happening. The lifter was just resting at the top and when I touched it it dropped (I have the rods and rockers out). So with my fingers pressing lightly on them, it appears #1 and #5 valves both move down to close at TDC.

I'm not sure what else to try here. I guess I could recheck compression with the gauge now but I don't understand what is going on with this engine.

 

Here's the PSI numbers for the cylinders:

1 - 35
2 - 34
3 - 41
4 - 29
5 - 25
6 - 31

This was done with all the plugs out and manifolds off and rockers out. And the leak down is still showing < 15% although I noticed that there is some piston movement during the test as they get pushed back down from TDC. Since the valves are closed all the time, I'm guessing that's ok. The leak down test gauge is zeroed out around 30 psi which also happens to be about where each cylinder sits with the compression test too. Perhaps higher pressure is just blowing by? If the truck hadn't been running well prior to this a few months back I'd assume there's something wrong with the block or the rings. And maybe there is,

I appreciate all the help. I'm not sure what to do at this point.

 

You can't do a compression test unless the valves are working, there is no pulled in air to compress

 

All these compression tests and leak down tests are meaningless without the valves working .

Put the lifters, pushrods and rockers back on, then run the tests.

 

Ok I didn't think of that during the compression test, but with the leak down test it should be fine because I'm injecting the pressure.

I pulled one of the heads off (1,2,3) to just visually verify TDC and see if everything visually looks ok with the gasket and valves. But that all looks ok. I soaked each cylinder in a light oil over night and rolled the engine over a few times just in case the rings are partially stuck. So I'll put it back together today and retest it.

------

Now I've put it back together the leak down was <5% probably helped by the layer of oil residue however with #1 at TDC and the rockers/lifters installed I noticed the intake was slightly depressed and that leak down result was >60% and when I spun the engine compression showed up 0 again. So I can only guess now that the timing must be slightly off. I guess this means I need to tear this thing down even further and open the timing cover to check the chain and timing gears.

 

You can not reuse the head bolts, right

And you have to use a new head gasket as well

Its not a time thing or use, the bolts are stretched when tighten to the correct torque, once that is done one time they can not be loosened and re-tightened because they are stretched already.

The head gasket is compressed when torqued down, once that is done it can't be uncompressed, it doesn't "spring back", so reusing it is not an option if you want it to seal

 

It may be too late, but if you still have the head off, turn it over (with the valves closed) and put some water there and see if the valve leaks.
VERY little seepage is OK, none is best.
A freshly rebuilt head with properly cut valves will hold gasoline.

 

Thanks for all the tips. Yes I have all new head bolts and gaskets ($$$). I did test the head with water and that's when I realized I needed the machinist to re-seat the valves. I just retested the valves on the one head with water and they were fine with no seepage (I also tested with gasoline and it was good too).

I'm going to start pulling parts off to get to the timing cover and see if I find anything. I have a new water pump too, so I'll put that in while everything is torn apart too.

 

What am I missing, if the valves passed the water and gas test, then why has the machinist re-seated the valves ?
So the one head was OK and the other was not ?
I thought you only pulled the one head ?

 

I'll try to recap. I pulled both heads had them resurfaced. Put everything back together and there was no compression at all (0 psi on all cylinders). Since the engine was running ok before I started all this (minus the coolant leak and bad head gaskets) I assumed the timing was probably ok. So I pulled the heads for a second time, checked valve seats with water and found them to leak. I assumed that was probably the problem and had the machinist do the valves. I put everything back together again thinking it was ok, but no compression again. So then I pulled everything except the heads and waited for a leak down tester to arrive. After testing I couldn't find a problem so I started to look closer at the timing and thought it was ok but I was most likely mistaken. After putting the rods and rockers back in at TDC I found the intake was leaking slightly. Since there was some compression with no rockers installed and none with rockers in place and the leak down was good with no rockers but bad with the rockers I've finally decided that there must be something going on with the timing. I pulled one head for the 3rd time just to double check everything because I'm new to this and probably too methodical. I confirmed TDC visually and I soaked the cylinders to help insure there wasn't an additional problem with the rings. I also rechecked the head again for leaks around the valves with water and gas.

So now I'm at the stage of checking the timing marks, keys, chain and gears on the engine. I did find that the water pump needed to be replaced as there was only one tiny little bit of fin left on the impeller. I suspect the engine probably did suffer from overheating, unfortunately. Tomorrow I should have the time to get the timing cover off and finally take a look at that part of the problem.

 

Some progress forward and some backwards. The impeller wore a few small holes in the timing cover which probably really didn't help the coolant leak into the engine. So I have to look into either repairing the cover or finding a new one.

Mainly though, the keys appear fine on both gears. I read the haynes method for setting the timing using the #5 exhaust rod so I guess I'll look at that. I was hoping I could do a quick visual and see a problem.

• What is the timing mark is on the crankshaft? Is it the keyway? The mark is clear on the camshaft gear.

Thanks again for all the help. I'm feeling pretty disheartened on this engine. It was going to just be a quick gasket change and purging oil....

 

Generally speaking, and in the case of the 3.0l Vulcan, OHV engines have timing marks with the key way on that gear

So cam key way would be at 6:00 and crank key way at 12:00