Compression test 01 Navigator

[Atman246]

As was said,check the valve spring. An easier way to locate the leak in the cylinder is to put air in and listen for the hissing. It's like a compression test in reverse. In the compression tester,there's a Schrader valve that needs to be removed. It's like the valve in a tire valve stem. Remove it,screw the compression tester into the plug hole and hook it up to a compressor with regulated air flow. Awesome job girl. Who needs a manicure?? My wife is 58 and runs a woodsplitter and a straight shaft weed wacker. That's what I brag about..

 

[Fordgirl01]

If that roller follower isn't in the cylinder head somewhere, that means someone else has been in there in the past and removed it for whatever reason.

I would inspect the cam for that valve looking for grooves, chips and cracks along the surface. If any are found the cam should be replaced. If you just install a new roller follower the cam would slowly grenade over time.

If there isn't any damage then you can replace the roller follower. Use assembly lube and coat the contact surfaces prior to assembly.

Ok-I manually turned the camshaft that the roller was under to get the teardrop shape on top. I did notice a scratch. I can feel it slightly when I rub my finger over it. Should that camshaft be replaced for a scratch like that (it’s like maybe a fingernail scratch-maybe a little deeper)? Also-I can’t see where that spring is broken. I even put the inspection camera down there. However, that spring seems shorter, more compressed than the other 15 springs.

I certainly want to do everything right considering how difficult it is to access this area-I don’t really want to do it again!

Thank you again everyone for your patience and knowledge

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[Fordgirl01]

Sorry about the repeated quote. I know how to edit posts but can’t seem to figure out how to delete it when I do that!!


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[stamp11127]

Reply deleted.

To do things right the cam should be replaced. Will it run without replacement? Yes, if the scratch has gone deeper than the hardening it will flake off small pieces of metal as it wears. That in turn can take the entire engine out if not caught by the oil filter. Plus you will have accelerated cam lobe wear.

Since the valve spring is possibly shorter than the others you may be able to move it up and down some in the head. If so, it is valve spring replacement time - with your fingers crossed the valve & seats aren't damaged.

 

[Fordgirl01]

Reply deleted.

To do things right the cam should be replaced. Will it run without replacement? Yes, if the scratch has gone deeper than the hardening it will flake off small pieces of metal as it wears. That in turn can take the entire engine out if not caught by the oil filter. Plus you will have accelerated cam lobe wear.

Since the valve spring is possibly shorter than the others you may be able to move it up and down some in the head. If so, it is valve spring replacement time - with your fingers crossed the valve & seats aren't damaged.

I can’t budge the spring. I even tried prying it a little and it doesn’t move. I would prefer to do this right as I intend to keep it-it’s rust free and not really high mileage.

So-how hard is a camshaft for this thing to come by? I did a quick search but nothing serious yet.


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[1955moose]

Try Parts Geek for your camshaft. I keyed in 99 Navigator, and they have cams that pop up.

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[stamp11127]

Don't get a cam just yet, you still need to determine why there isn't any compression in that cylinder. If it isn't from a leaking valve then it is in the bore.
If you can the next step would be to bring the #8 cylinder to tdc and hit it with compressed air through the spark plug hole. Where you hear the air leaking tells you where the problem is.

 

[TobyU]

Now we are getting somewhere.
Usually when a follower/rocker pops off ( well ,maybe not usually but often) there is no valve spring or seat (popped) or cam damage.

Compression is a funny thing. I can't remember from the previous page pics if it's an intake or exhaust valve we are concerned about.
If we have sealed closed valves....If an intake follower is off ...you can't suck any air in for it to compress so you will have very low reading.
If exhaust then you will have plenty of compression as it compresses the air the intake valve lets in but you get another compression on the exhaust stoke as it can't exit through open exhaust valve.

An intake will cause the needle (on most gauges) to go up and suck back down hard then back up instead or pulse up up up.
It will also suck really hard if you put a hose or rubber plug on a stick down there.
This is what I was talking about way earlier in the thread.

The valve spring looking lower concerns me.
That would mean it is not coming up (closing) all the way. This is usually from a popped valve seat, or slipped valve guide or bent valve on engines in general but I have never seen any of these on a ford modular so I don't know what it most likely.

As Stamp ans others have said, now you need to put air into the plug hole to see where it comes out.
My guess (unfortunately) is you will hear air escaping out intake or exhaust. I'm guessing exhaust.
10-15 psi should do it don't crank it wide open into it.
You can push down on the valve when the air is going in and hear the air flow then be sealed off.

It is possible to have a broken spring too (are those dual or single ones?) and the valve be stuck by the spring. That right now would be your luckiest thing.

The air is what you use to hold the valves for that cyl closed if you remove the spring.

If you have sealing valves and no broke springs and the cyl holds air then you I would put a new follower and lifter(they call them lash adjuster I think)as you can't trust the old ones and they are cheap parts even at Ford dealer.
THEN you do compression test and it you get 120 + you are happy.

If this were the case I would not worry about the cam scratch.I would dress it with an emery board (I use them all the time but not on my nails) then a red scotchbrite pad to polish it then some metal polish or a dremel polish wheel but a rag and your finger with polish will be ok.
That lifter roller wheel is very hard and there is little friction between the two.
If everything goes in your favor and you don't have to pull cam or head and you keep the cam just run some full syn oil in it.

If it doesn't hold air or if you have to investigate spring much I think you'll have to pull cam on the dreaded 32v to see anyway. If it's out you and you fix the rest you can probably get a used cam fairly cheap---BUT 32v again so what do I know.
I hate them even though I have one in the driveway. Give me a 4.6 (YEAH) or a 5.4 16v (less YEAH) any day!!

Good luck and GREAT job so far!!!!

 

[rjdelp7]

I don't see how a scratch on the cam, makes it bad. Its a roller follower and is covered in oil. The scratch is in direction of movement, not across the lobe. The video on youtube, has a guy wrenching, that claims the exhaust valves leak on these motors. He doesn't explain why. A another guy on youtube claims, fixing a poorly maintained Ford modular is a waste and always replaces them(that is what dealers usually do). My guess is, it probably burns a lot of oil and got ran one too many times low. So you can go through all this trouble and have more problems. If its the spring, fix it and put back together. Don't get in, upside down on it.

 

[stamp11127]

The old days of flame hardening has been replaced in some areas with induction hardening. Unfortunately that only goes a few thousandths deep into the metal. If the scratch has breached the hardend layer the cam will slowly grenade.

 

[Fordgirl01]

Thanks again for the wealth of info all of you share.

TobyU-I always love your thinking out loud posts! My brain works the same way so I get a lot out of your advice. I don’t know if it’s an intake or exhaust valve-how do you tell. If it’s from location, it is a valve on the lower (towards the drivers side fender) side. When I did the compression test (seems like ages ago), the needle did not even move-on either wet or dry test on this cylinder. Dual or single springs-I only see one per valve (obviously 4 per cylinder on this).

rjdelp-I really don’t think this vehicle was poorly maintained. I do have a few records for it and it appears it was pretty well taken care of. I don’t believe it burned oil, but of course I don’t know for sure. I will try to find some info on the leaky exhaust valves for this motor-thank you for the suggestion.

So I will plan on the air test and report how it goes and we’ll go from there!!


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[rjdelp7]

The old days of flame hardening has been replaced in some areas with induction hardening. Unfortunately that only goes a few thousandths deep into the metal. If the scratch has breached the hardend layer the cam will slowly grenade.

In a mass produced engine, I thought the cams are made of hardened, high carbon, tool steel. GM had issues in the mid 1970's with 'soft cams' mixed with low oil pressure. They were cheap, cast iron, 'flame hardened'. They fixed the problem with better steel and a better lubrication. Hardened steel has more carbon and is manufactured for strength. So technically, wouldn't the entire cam, be made from the same material? If this engine got to the point of losing compression and breaking valves, its probably toast. If she can get it running for cheap(temporary), she can buy time to find an other engine.

 

[TobyU]

In a mass produced engine, I thought the cams are made of hardened, high carbon, tool steel. GM had issues in the mid 1970's with 'soft cams' mixed with low oil pressure. They fixed the problem with better steel and a better lubrication. Hardened steel has more carbon and is manufactured for strength. So technically, wouldn't the entire cam, be made from the same material? If this engine got to the point of losing compression and breaking valves, its probably toast. If she can get it running for cheap(temporary), she can buy time to find an other engine.

I don't think the cam will cause any big issue either but I think she has other issues with it.

 

[TobyU]

Thanks again for the wealth of info all of you share.

TobyU-I always love your thinking out loud posts! My brain works the same way so I get a lot out of your advice. I don’t know if it’s an intake or exhaust valve-how do you tell. If it’s from location, it is a valve on the lower (towards the drivers side fender) side. When I did the compression test (seems like ages ago), the needle did not even move-on either wet or dry test on this cylinder. Dual or single springs-I only see one per valve (obviously 4 per cylinder on this).

rjdelp-I really don’t think this vehicle was poorly maintained. I do have a few records for it and it appears it was pretty well taken care of. I don’t believe it burned oil, but of course I don’t know for sure. I will try to find some info on the leaky exhaust valves for this motor-thank you for the suggestion.

So I will plan on the air test and report how it goes and we’ll go from there!!


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You are one of the few! Lol I ramble on and spew off topic info....as you said, thinking out loud.

Remembering now this is a 32 v so 2 intakes and 2 exhaust valves.
You can look up a diagram for valve orientation or look to see which one i tin the intake runner of the head and which ones are closest the exhaust ports.

If one is lower than other it is probably stuck open and this would give 0 compression.

This is a little unorthodox but if you you can get the valve to close and seal----you COULD leave it closed and the follower off and still run pretty well.

As long as the valve is closed....A non opening valve on a 4 valve..the other valve will still let air in and out just not quite as much. It's not like half. More volume will go in or out the only one that is open and I bet on many engines if you disabled one intake or exhaust (esp exhaust) you couldn't even tell.

But the ? is why is it open if open. If has to seal almost perfectly.
A valve that looks closed but only has a sliver of light getting through will kill your compression.

DO the air test to see where it is leaking and we'll go from there.

 

[Fordgirl01]

I think I have a distinct advantage from my lack of experience. Since I’ve never gotten into a motor any further than spark plugs-I have nothing to compare this 32 valve to. Sooooo, I am completely ignorant to the apparent difficulty as compared to other motors (I can just assume they are all this complicated in my own little world)! That’s my glass is half full attitude[emoji16]

And-what is the worst that could happen? I’d give up (not very likely) and either have someone come out to back together or sell it like it is.


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[TobyU]

One of these days in the future you should pull

I think I have a distinct advantage from my lack of experience. Since I’ve never gotten into a motor any further than spark plugs-I have nothing to compare this 32 valve to. Sooooo, I am completely ignorant to the apparent difficulty as compared to other motors (I can just assume they are all this complicated in my own little world)! That’s my glass is half full attitude[emoji16]

And-what is the worst that could happen? I’d give up (not very likely) and either have someone come out to back together or sell it like it is.


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One of these days in the future you should pull a motor out of an expedition Navigator or an F-150. After you do it. You might decide like me and then it's almost easier just to pull the engine and do all the work on the stand as opposed to trying to pull ahead in the chassis.
At the point you're at now it's about Breakeven. You've got about as much time and aggravation in it as it would have taken to pull the engine and if you can fix it it's probably the best way like if that was just a popped off follower which often happens to people with no real damage anywhere else and no valve stuck open. But if you have to remove the head. That means you have to do a lot more work That makes having it out and honest and so much more attractive.
I'm not real sure if it's possible to pull a head off without removing the timing chain cover and the timing chains but I don't think many people do it that way. You might be able to unbolt the cam and lift it up out of an angle out of the way and get the head in with another person but it might be an impossibility. I have never tried. All the work I have done on them has been out of the truck and on an engine stand.

 

[Fordgirl01]

One of these days in the future you should pull

One of these days in the future you should pull a motor out of an expedition Navigator or an F-150. After you do it. You might decide like me and then it's almost easier just to pull the engine and do all the work on the stand as opposed to trying to pull ahead in the chassis.
At the point you're at now it's about Breakeven. You've got about as much time and aggravation in it as it would have taken to pull the engine and if you can fix it it's probably the best way like if that was just a popped off follower which often happens to people with no real damage anywhere else and no valve stuck open. But if you have to remove the head. That means you have to do a lot more work That makes having it out and honest and so much more attractive.
I'm not real sure if it's possible to pull a head off without removing the timing chain cover and the timing chains but I don't think many people do it that way. You might be able to unbolt the cam and lift it up out of an angle out of the way and get the head in with another person but it might be an impossibility. I have never tried. All the work I have done on them has been out of the truck and on an engine stand.

Note to self......add engine stand to my Christmas wish list!!


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[TobyU]

Note to self......add engine stand to my Christmas wish list!!


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Get a used one on Craigslist or Marketplace. I got my last one for 40. Sometimes they are 30-35.
A 4 leg is better than 3 and probably worth a little extra. Harbor Freight it always a good option too.

 

[Fordgirl01]

When I put air in the spark plug hole to test for leaks do I first need to get the piston to TDC, or is that only necessary when changing the valve spring? I’ll probably give this a try after work tonight.


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[stamp11127]

TDC on compression stroke. Cam lobes for that cylinder will be pointing away from the head.