98 Ford F150 4.2 v-6 help....

ghost

ghost

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Location
Hartsville/Camden,SC
So my FIL had this truck and my step son was given it to help him out. It died on him and they thought it was the flexplate... Well I pulled the starter and saw no damage so I swapped it out. Ended up fixing the no start. I drove it to lunch today and at times it would vibrate. Some times just idling others when it would feel like it shifted into OD. From what I have been told before the FIL passed last year this truck had a motor put in it and a transmission at some point. So I think it's running on 5 instead of 6 for one thing. It had a PO171 and PO 174. Both banks lean. I put a fuel filter on it and that is it. Is there an easy way to determine if it's truly running on less then 6? I really do not want to put too much effort into this thing. It's running and driving but very rough at times..... Any advise would be great.....
 
Do a compression test on it...and a leak down test. Did you check for spark on all cylinders? Did you check the plugs? Did they all look the same?
 
Check intake gaskets... (Pressure test cooling system) they will also cause no starts. And broken flywheel teeth. And lean codes. Of course a dirty maf can cause lean codes also.. but you'd have to check the freeze frame to see when it's running lean.. at idle? After extended run time? On cold starts?
 
If it's a 98, it should likely be throwing misfire codes if it's down a cylinder. I'm not sure the specifics of how Ford implemented their obd2 misfire detection back then though.
 
1stgenxxx said:
Do a compression test on it...and a leak down test. Did you check for spark on all cylinders? Did you check the plugs? Did they all look the same?
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I can do a spark test and compression test. Never done a leak down test.

a_kelley said:
Check intake gaskets... (Pressure test cooling system) they will also cause no starts. And broken flywheel teeth. And lean codes. Of course a dirty maf can cause lean codes also.. but you'd have to check the freeze frame to see when it's running lean.. at idle? After extended run time? On cold starts?
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I suspect an issue because I failed to mention he said it blew white smoke and used coolant. Read a MAF would cause those codes. No broken teeth on flywheel that I can find. Starts fine just runs rough.

Fabrik8 said:
If it's a 98, it should likely be throwing misfire codes if it's down a cylinder. I'm not sure the specifics of how Ford implemented their obd2 misfire detection back then though.
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I did not realize it would throw a code for that.

Thanks that gives me a place to start. I guess I need to pull plugs and look at them.....
 
I bet it's the intake gaskets, cause they will dump coolant straight into the intake port. Pass leak down and compression test though if it is the case. Motors were known as rod benders for the intake issue. Would also pull coolant in under vacuum..
 
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Pulled a plug and tested compression on it.
 
I might be interested in it if it's a extended cab or crew cab and short bed.. and is it 2 or 4 wheel?

You might do a wet compression test on it, coolant will wash the cylinders....
 
a_kelley said:
I might be interested in it if it's a extended cab or crew cab and short bed.. and is it 2 or 4 wheel?

You might do a wet compression test on it, coolant will wash the cylinders....
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Could the coolant really make that much of a difference in cylinder to cylinder compression readings?
I cant think of anything that would show these symptoms, other than a leaking head gasket????
 
junkxj said:
Could the coolant really make that much of a difference in cylinder to cylinder compression readings?
I cant think of anything that would show these symptoms, other than a leaking head gasket????
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When I was starting on mechanics.... I remember vividly a kia car that had water for fuel... Wouldn't hit on starting fluid. Did compression test, showed low low <30 psi. Figured the belt went. It went to another shop that checked the fuel, did a wet test and drained and refilled tank and it was going again. The 4.2 intake gasket design will literally dump coolant straight into the intake port. I have seen head gaskets bad enough to leak enough to wash cylinders as well, but wasn't a 4.2 Ford v6..

If you pressure test the cooling system for a while, then bar the motor over, you may find the coolant in the cylinders when the intake valve opens.. though if that's the case, should be cylinders 1/3 or 4/6 pic for reference..
Screenshot_20190329-001127s.png
 
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a_kelley said:
I might be interested in it if it's a extended cab or crew cab and short bed.. and is it 2 or 4 wheel?

You might do a wet compression test on it, coolant will wash the cylinders....
Click to expand...
2WD Extended cab long bed. I did not even think to do a wet test. I'm betting its the head gasket. I swear I smelled exhaust in the coolant bottle....
 
This truck will be sold. If anyone is interested let me know. Lets start at $1250 OBO. @a_kelley you expressed some interest but have not responded to my pm's. I have a signed SC salvage title in hand.
 
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