Bronze Valve Guide Wear

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3
Location
PA
Hello all. Long-time lurker, first-time poster. I have an issue that I think people here could certainly offer educated opinions on. I have a Plymouth Horizon in which I swapped a Chrysler 2.4L DOHC. It's got a big turbo and makes in the neighborhood of 500-550 hp judging by 143mph trap speeds. It typically does not see a large number of road miles, but last year I ran Hot Rod Drag Week with it. With a total of about 1200 miles and maybe 2 dozen drag strip passes on it, I noticed quite a bit of carbon build up on the pistons. I pulled the head off and sent the head out to get checked, and the found it had large amounts of valve guide wear. They are manganese bronze, and the valves are stainless steel. It was an expensive rebuild. The cause was inconclusive and would like to prevent it from happening again. I had been using Mobil 1 5w30 full synthetic. I was thinking that something with a higher zinc content might help. Any opinions and suggestions would be welcome. Thank you.
 
If you want to stay with Mobil 1 you could consider Mobil 1 ESP. But certainly there are plenty of other choices with high zinc and phosphorus to choose from.

Mobil 1 ESP.PNG


Mobil 1 0W40 ESP.PNG
 
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2,872
Location
High Tax Illinois
Are you running posi-lock valve seals? At least that's what we used to call them. Zero oil gets by. Might ask the engine builder if there is a better way to seal and letting just a tad oil to lube the valve stems.
 
Messages
5,333
Location
Paramount, California
I don't think antiwear additives such as ZDDP have anything to do with it. If the wear is corrosive, you will need a high-TBN full-SAPS oils such as the Mobil 1 FS 0W-40 A3/B4, FS meaning full-SAPS, and shorter OCIs. Bronze, copper, lead, etc. can experience corrosive wear. The higher alkalinity (higher detergent content) of full-SAPS oils will protect against this. It could also be not an oil-related issue but an issue with the valve-stem oil seals or some other rebuild issue as others said. There is a good discussion on bronze valve-guide failures in this forum. It's probably not oil-related: Let's talk about valve-guide wear -- Don Terrill's Speed Talk
 

MolaKule

Staff member
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21,912
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Iowegia - USA
Originally Posted by Chris142
Thats weird. Those guides are supposed to be self lubricating. Could the machine shop have goofed the first time? Super stiff valve springs causing side load?
My thoughts as well: Excessive Side loads
 
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5,570
Location
New Zealand
Rockers cause guide wear as they push and pull the valve stem. DOHC should be buckets and so no side loads...although I don't know that engine at all, unless it's a badged Mitsubishi engine.
 
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5,333
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Paramount, California
OK, look what I've found! This paper says moly causes severe corrosion and wear, resulting in subsequent failure, in brass pins in diesels engines. Some effects of zinc dithiophosphates and detergents on controlling engine wear Extreme temperatures in your racing engine would exaggerate the corrosion and wear of brass by the moly. Mobil 1 contains trinuclear moly, which is a form of molybdenum dithiophosphate -- a destroyer of bronze according to the paper. I recommend you use a moly-free oil next time. Castrol Edge 0W-40 A3/B4, sold at Walmart, is a good moly-free, full-SAPS oil suitable for your application.
 
Messages
5,333
Location
Paramount, California
Originally Posted by Gokhan
Mobil 1 contains trinuclear moly, which is a form of molybdenum dithiophosphate -- a destroyer of bronze according to the paper. I recommend you use a moly-free oil next time. Castrol Edge 0W-40 A3/B4, sold at Walmart, is a good moly-free, full-SAPS oil suitable for your application.
According to its patent, the trinuclear moly is probably a molybdenum dithiocarbamate (MoDTC) rather than a molybdenum dithiophosphate (MoDTP), but the actual commercial formula is unknown. Infineum trinuclear moly presentation Nevertheless, this Vanderbilt patent says all moly types can cause high-temperature copper (therefore, copper alloys such as bronze) corrosion and discusses ways to reduce it by combination of different moly types and other additives. Vanderbilt patent: Copper corrosion with sulfur-containing and sulfur-free moly and triazole Give the moly-free, full-SAPS Castrol Edge 0W-40 A3/B4 a try.
 
Messages
25,970
Location
MA, Mittelfranken.de
Originally Posted by contraption22
Hello all. Long-time lurker, first-time poster. I have an issue that I think people here could certainly offer educated opinions on. I have a Plymouth Horizon in which I swapped a Chrysler 2.4L DOHC. It's got a big turbo and makes in the neighborhood of 500-550 hp judging by 143mph trap speeds. It typically does not see a large number of road miles, but last year I ran Hot Rod Drag Week with it. With a total of about 1200 miles and maybe 2 dozen drag strip passes on it, I noticed quite a bit of carbon build up on the pistons. I pulled the head off and sent the head out to get checked, and the found it had large amounts of valve guide wear. They are manganese bronze, and the valves are stainless steel. It was an expensive rebuild. The cause was inconclusive and would like to prevent it from happening again. I had been using Mobil 1 5w30 full synthetic. I was thinking that something with a higher zinc content might help. Any opinions and suggestions would be welcome. Thank you.
Which guides were worn more the intake or the exhaust or were they pretty much equal?
 

contraption22

Thread starter
Messages
3
Location
PA
Thanks everybody for your input. As far as I know, the valve seals were typical shelf replacements. Nothing special. This is a Chrysler engine. Not a 4G63 derivative. Although the 2,0L version of this engine was used in some Diamond Star vehicles.
Originally Posted by Trav
Which guides were worn more the intake or the exhaust or were they pretty much equal?
Some were worn more than others, but the exhaust were worn slightly more.
 
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25,970
Location
MA, Mittelfranken.de
They were possibly a little too tight to begin with, if these were iron guides the valve faces and seats would probably be damaged as the iron does not have any self lubricating properties and would just bind the stem when it got hot. In this case the manganese bronze material does so it fortunately just wore the new guides out quickly. I see the head uses slippers so side loading damage from cam rotation is not as big an issue as it would be with bucket and shim. The fact you are making that much HP from this engine with forced induction really changes things, I would talk to the builder/engine machinist about possibly running clearances in the guides similar to that of a diesel. Like engine bearings a little tight is not good, they will not size themselves with wear to the optimal clearance, the wear will not be uniform and the stem will bounce around in there like kids in a bouncy house causing more and more wear. I seriously doubt this type of wear is a result of oil type or viscosity. 2cents
 
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5,333
Location
Paramount, California
Originally Posted by Trav
They were possibly a little too tight to begin with, if these were iron guides the valve faces and seats would probably be damaged as the iron does not have any self lubricating properties and would just bind the stem when it got hot. In this case the manganese bronze material does so it fortunately just wore the new guides out quickly. I see the head uses slippers so side loading damage from cam rotation is not as big an issue as it would be with bucket and shim. The fact you are making that much HP from this engine with forced induction really changes things, I would talk to the builder/engine machinist about possibly running clearances in the guides similar to that of a diesel. Like engine bearings a little tight is not good, they will not size themselves with wear to the optimal clearance, the wear will not be uniform and the stem will bounce around in there like kids in a bouncy house causing more and more wear. I seriously doubt this type of wear is a result of oil type or viscosity. 2cents
Wouldn't it be pretty obvious when you slided the valves in if the clearance was too tight? I just checked the thermal-expansion coefficients for manganese bronze, engine-valve stainless steel, and aluminum, and I don't see a problem. There could be some other problem with this cylinder head or valvetrain. Nevertheless, I would definitely try the moly-free, full-SAPS quasi-German Castrol 0W-40 A3/B4 in this application.
 
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725
Location
Northeastern Vermont
Originally Posted by oldhp
Are you running posi-lock valve seals? At least that's what we used to call them. Zero oil gets by. Might ask the engine builder if there is a better way to seal and letting just a tad oil to lube the valve stems.
Excellent answer. I rebuilt cylinder heads for 30 years. I would install bronze guides either spiral inserts or solid bronze guides on all high performance engines (drag racing-circle track. I would set clearance on intake valves at 0.001 to 0.0015 with an umbrella seal never an pc seal ( positive control). Exhaust valves clearance would be 0.002 without a seal. Never had any issues
 
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Messages
5,333
Location
Paramount, California
Originally Posted by littleant
Originally Posted by oldhp
Are you running posi-lock valve seals? At least that's what we used to call them. Zero oil gets by. Might ask the engine builder if there is a better way to seal and letting just a tad oil to lube the valve stems.
Excellent answer. I rebuilt cylinder heads for 30 years. I would install bronze guides either spiral inserts or solid bronze guides on all high performance engines (drag racing-circle track. I would set clearance on intake valves at 0.001 to 0.0015 with an umbrella seal never an pc seal ( positive control). Exhaust valves clearance would be 0.002 without a seal. Never had any issues
I agree that having no valve-stem oil seals at all will not cause a problem for racing engines, and it will increase the lubrication of the valves. They are mainly needed to control the oil passage and consumption during idle or other high-vacuum conditions in on-road production engines.
 
Messages
25,970
Location
MA, Mittelfranken.de
Originally Posted by Gokhan
Originally Posted by Trav
They were possibly a little too tight to begin with, if these were iron guides the valve faces and seats would probably be damaged as the iron does not have any self lubricating properties and would just bind the stem when it got hot. In this case the manganese bronze material does so it fortunately just wore the new guides out quickly. I see the head uses slippers so side loading damage from cam rotation is not as big an issue as it would be with bucket and shim. The fact you are making that much HP from this engine with forced induction really changes things, I would talk to the builder/engine machinist about possibly running clearances in the guides similar to that of a diesel. Like engine bearings a little tight is not good, they will not size themselves with wear to the optimal clearance, the wear will not be uniform and the stem will bounce around in there like kids in a bouncy house causing more and more wear. I seriously doubt this type of wear is a result of oil type or viscosity. 2cents
Wouldn't it be pretty obvious when you slided the valves in if the clearance was too tight? I just checked the thermal-expansion coefficients for manganese bronze, engine-valve stainless steel, and aluminum, and I don't see a problem. There could be some other problem with this cylinder head or valvetrain. Nevertheless, I would definitely try the moly-free, full-SAPS quasi-German Castrol 0W-40 A3/B4 in this application.
It would not be obvious at room temperature. Steel expands the most of the materials being used and when subjected to higher than normal street engine temps can close the gap and bind. One way of minimizing this is to use sodium filled stems on the exhaust valves.
 
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5,333
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Paramount, California
Originally Posted by Trav
It would not be obvious at room temperature. Steel expands the most of the materials being used and when subjected to higher than normal street engine temps can close the gap and bind. One way of minimizing this is to use sodium filled stems on the exhaust valves.
I've checked the thermal-expansion coefficients. Engine-valve stainless steel expands less than manganese bronze, and manganese bronze expands less than aluminum. However, this is assuming that the valves and guides are at the same temperature. Valves probably run a lot hotter than the guides. So, that could be an issue.
 
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25,970
Location
MA, Mittelfranken.de
The valves run hotter, much hotter especially the exhaust, that's why I asked him which ones had more wear. Sodium filled valves may offer a partial solution, he needs to discuss this with the machinist/builder IMO.
 
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