Compression test 01 Navigator

[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.