Burned Valve
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How do you know it has a burned valve??
If your getting chuffing from exhaust or loud woofing from the intake...... it could be worn valve guides.
Only problem is IF it is valve guides and the valves drop and stay out of place KABOOM.
Read this great info....... I think the company is no longer in business.
TheDieselStop.Com - www.thedieselstop.com
If your getting chuffing from exhaust or loud woofing from the intake...... it could be worn valve guides.
Only problem is IF it is valve guides and the valves drop and stay out of place KABOOM.
Read this great info....... I think the company is no longer in business.
TheDieselStop.Com - www.thedieselstop.com
It sure can. If that is truly your problem, once a valve is burned bad enough to be noticable (dead cylinder) that's a sure sign there's very little seating surface between the valve and it's seat allowing way less than normal heat transfer. If you continue to drive it to a significant extent the valve can severely overheat and melt, break, or slough off pieces of the valve head.
Thanks for the replies! The description of the progression of worn valve guides is exactly what has happened! I am at stage 3 a will stop driving Imediately!!
Heres how I determined have a valve issue on #8 ehhaust.
I have a 1990 F250 with a 7.3 idi, 265,000. I have been noticing a rough idle for a while and a funny sound out the exhaust on the drivers side. I replaced the injection pump a little while ago so I thougt it was time to replace injectors. I replaced the injectors and still have the rough idle. I performed a compression test the low was 450 and the high was 490 with all others inbetween except one at 220, #8. I put air into the cylinder and with both valves closed, as best i could tell, I could hear a hiss out the exhaust and what seemed to come from around the valve stem? I concluded I have a burned exhaust valve but I want to be sure. I understand somthing had to happen to cause this valve to burn??
Heres how I determined have a valve issue on #8 ehhaust.
I have a 1990 F250 with a 7.3 idi, 265,000. I have been noticing a rough idle for a while and a funny sound out the exhaust on the drivers side. I replaced the injection pump a little while ago so I thougt it was time to replace injectors. I replaced the injectors and still have the rough idle. I performed a compression test the low was 450 and the high was 490 with all others inbetween except one at 220, #8. I put air into the cylinder and with both valves closed, as best i could tell, I could hear a hiss out the exhaust and what seemed to come from around the valve stem? I concluded I have a burned exhaust valve but I want to be sure. I understand somthing had to happen to cause this valve to burn??
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Until you take the head off or take a look with a borescope, you can't say if it's a burnt valve or a valve guide gone bad causing your valve not to seat. Head removal is a given at this point though.
Would you do both sides? How much life do you think is left in this engine with 265,000 miles.
I'm looking at another engine with 125,000 that I can get for $200. It has what seems like oil residue all over the fan shroud and front of engine and a lot of oil on the intake by the, i'm not sure what its called, thing that recirculates crancase vapors? I'm thinking this is a sign of blowby? Its in a 89 ambulance.
I'm looking at another engine with 125,000 that I can get for $200. It has what seems like oil residue all over the fan shroud and front of engine and a lot of oil on the intake by the, i'm not sure what its called, thing that recirculates crancase vapors? I'm thinking this is a sign of blowby? Its in a 89 ambulance.
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17,585 Posts
It's your call, but If it were me I would be real tempted to buy the ambulance engine as a spare at least. 260,000 miles on a maintained IDI isn't that far into it's life span. Plenty of members here with 500,000+ miles on theirs.
You would need to find the source of the oil leak, but the part you describe is the CDR ( Crankcase Depression Regulator) same thing as a PCV valve. there is a test for excess blowby but the engine needs to be running to do it.
You would need to find the source of the oil leak, but the part you describe is the CDR ( Crankcase Depression Regulator) same thing as a PCV valve. there is a test for excess blowby but the engine needs to be running to do it.
Thank you for advice. I'm leaning towards the ambulance engine as well but I want to sewap motors an and keep my current one for a spare. Looks easier to r&r the engine to do the valve job anyway.
Im going this weekend to see it run. I've read lots of different ways to determine blow by. What method do you recommend?
Im going this weekend to see it run. I've read lots of different ways to determine blow by. What method do you recommend?
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17,585 Posts
37+ yrs of working on cars allows me to make some educated guesses based on standing in front of the engine running. The true method involves the use of a nanometer and that is something I don't have.
If I was standing in front of the engine running, I would be looking at the volume of oil mist and I would probably put my hand over the hose and see how much pressure there is..But again that goes along with almost 40 years of "feeling" pressures and such.
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12,232 Posts
You would need to determine if the ambulance is Fseries (truck cab) or E series (van cab).... the engines are slightly different. Fuel filter is on Pax side on the F series and on the drivers side for E series. The oil coolers are different also......
Thanks again for the replies. It is a econoline not a truck. I assuming that parts are interchangable?
Blow by is my biggest concern. Does this CDR require replacement on a regular basis like a PVC valve? Could it be deffective/dirty causing the excess oil?
Blow by is my biggest concern. Does this CDR require replacement on a regular basis like a PVC valve? Could it be deffective/dirty causing the excess oil?
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12,232 Posts
Do you know when to service your CDR valve?
All 6.9L and 7.3L diesel engines are equipped with a CDR (Crankcase Depression Regulator) valve. Even the new 7.3L Power Stroke is also equipped with the same valve. The CDR valve is one of the leading causes of head gasket failure in these engines. The CDR valve is responsible for controlling the pressure/vacuum in the engine crankcase, and seperating the oil mist from the air and returning the oil to the crankcase. The CDR valve should be serviced every second oil change or when signs listed below are seen.
When the CDR valve is not properly serviced, engine oil enters the air intake and is drawn into the engine. The diesel engine will burn this oil as fuel, however, it is heavier and thicker than diesel fuel and, having greater BTU output, causes excessive heat in the cylinder. Due to the intake manifold design, most of the oil will migrate to #7 and #8 cylinders; the last two cylinders in the rear by the firewall. The increased temperature here will cause the cylinder head to lift off the gasket and allow water or oil to leak out the back of the cylinder head where it meets the block.
To check your CDR valve, remove the air cleaner hold down bolt and inspect it. If the bolt is covered with engine oil mist, it's time to service your CDR valve! Ford calls this item a "Adapter assembly for Crankcase Ventilation" Part number E3TZ-6A665-A or IH part #1805319C1
To service the CDR wash with a solvent, allow to dry, do not use compressed air to dry. There is a small hole in the CDR back cover, ensure it is clean and open. If black chunks of rubber are visible in the intake, on the screen then the rubber membrane has disintegrated, replace the CDR.
All 6.9L and 7.3L diesel engines are equipped with a CDR (Crankcase Depression Regulator) valve. Even the new 7.3L Power Stroke is also equipped with the same valve. The CDR valve is one of the leading causes of head gasket failure in these engines. The CDR valve is responsible for controlling the pressure/vacuum in the engine crankcase, and seperating the oil mist from the air and returning the oil to the crankcase. The CDR valve should be serviced every second oil change or when signs listed below are seen.
When the CDR valve is not properly serviced, engine oil enters the air intake and is drawn into the engine. The diesel engine will burn this oil as fuel, however, it is heavier and thicker than diesel fuel and, having greater BTU output, causes excessive heat in the cylinder. Due to the intake manifold design, most of the oil will migrate to #7 and #8 cylinders; the last two cylinders in the rear by the firewall. The increased temperature here will cause the cylinder head to lift off the gasket and allow water or oil to leak out the back of the cylinder head where it meets the block.
To check your CDR valve, remove the air cleaner hold down bolt and inspect it. If the bolt is covered with engine oil mist, it's time to service your CDR valve! Ford calls this item a "Adapter assembly for Crankcase Ventilation" Part number E3TZ-6A665-A or IH part #1805319C1
To service the CDR wash with a solvent, allow to dry, do not use compressed air to dry. There is a small hole in the CDR back cover, ensure it is clean and open. If black chunks of rubber are visible in the intake, on the screen then the rubber membrane has disintegrated, replace the CDR.
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