Fuel System: fuel pump injecting oil into fuel?

[Paul Keller]

Have been disassembling my 1963 289 looking for the source of oil contamination into the recently rebuilt engine (bored, new pistons, rings & bearings done by a Stude' shop. Heads rebuilt by a local long time engine shop - All work seems excellent and to Stude' specs (parts, sizes, clearances). The oil use is thru' the engine (no visible leakage), began approx. 3,000 miles after rebuild and has increased noticeably with use - Great clouds of blue smoke!
This problem was posted previously and now am into the process of engine tear down.

A current post (04-08-22 03-06 @ AM by E. Davis) regarding replacement/import fuel pumps) notes the possibility of the pump injesting engine oil into the fuel. I have not heard of this problem occurring (gas into the oil pan is usually the problem) - Is it an actual potential problem, or am I misunderstanding the description?

Thanks as always to the Stude' community,
paultk

[Jeffry Cassel]

I do not see how this can occur as there is pressure on the fuel side of the pump, albeit only 3-5 psi and no pressure on the timing gear cover side. Check pcv valve. Just disconnect it, plug the hole in carb and start car. Check compression if pcv is OK. I had a piston blow out on a Case 1070 many years ago. The IH shop had done a top overhaul on it . They had lined up the ring gaps perfectly and right at the wrist pin ,too! Blew the piston out right there. And, of course, they refused to warranty their work. A 'leak down' test might be helpful. This is an unusual situation and is most likely going to mean tearing down the engine all over again . But start with pulling the heads: that'll only take an hour and most likely will give you the answer. Any warranty? Or like the IH shop. (There was a reason for IH to fail-bad engineering and really poor customer service because their tractors sucked) If no warranty do not take it back to that shop. Studebaker West is in CA and they have a shop but don't know how far away you are. Call them anyway; they are always very helpful. (Don't have to tear down bottom end- I don't think anything down there is going to cause it to smoke. Is head gasket OK- are heads true?)

















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[E. Davis]

In reference to Paul's post my fuel pump is leaking from around the arm pin to the outside and has no connection to oil getting into the fuel system.

[RadioRoy]

The fuel pumps that allow the engine to ingest oil are the dual action pumps with auxiliary vacuum pumps for vacuum windshield wipers.

Do you have a dual action fuel pump for vacuum wipers?

Do you have a Hydrovac power booster for the Brakes?

Do you have a PCV system for smog control?

Do the rocker arms have the correct bolts holding them down and do the heads have new valve seals?

[Paul Keller]

Post #2: Am now in the process of tear-down - Carb, Intake and Lifter valley cover Rocker arms and stands removed - heads are next. So far all looks OK. (Slow work as the parts are being cleaned and inspected as they are removed).
Post #3: Pump is Single action (no vacuum booster). No vacuum boost power brakes. PCV has been tested by disconnecting and plugging ends, No smoke out of cover vents (This is a 1963 Calif system w/ a PCV valve and valve cover breathers). Correct valve stand bolts, all properly torqued. New stem seals (replaced twice - No change), Valve guides new with approx. .0018 - .0024" side clearance.
Thanks for keeping me on-track,
paultk

[christophe]

Did you examine the spark plugs to determine if the trouble affected all cylinders or only one?
Did you made a compression test or hook a vacuum gauge to the engine?
If blue smoke occured upon acceleration, rings are most likely the culprit. If this happened after descending a hill using engine braking, oil is being sucked via the valve guides.

[jackb]

How recent a rebuild ? Might there be some break-in issue ?

[JoeHall]

Never heard of a failing mechanical pump pumping oil into the fuel, rather, it pumps gas into the oil. The first clue is if the oil smells of gasoline, and / or the oil level rises, instead of lowering, as miles add up. Then too, gasoline contaminated oil will cause smoke, as it gets past the oil rings. An electrical pump does not have this problem. I have not ran a mechanical pump since the 1980s, and would not install one if given to me.

[JoeHall]

As for the motor not breaking in properly, do you know which type of piston rings were used? What grit were the cylinders honed with, for final hone? How many miles since the rebuild? What is average operating temp, and ambient temp?

[Paul Keller]

Re: post #5- All cylinders are affected, Smoke occurs at all times; Idle, acceleration, coast down. Only time smoke is minimal is at fresh start-up, for approx the first few minutes (Note: looking thru' plug holes all cyls' have wet oil at bottom of reverse dome - it looks like and feels like and tastes like engine oil - NOT coolant). Do not have comp tests handy, but all were within 9 PSI and recall @ approx 150 - 160 psi. Same w/ idle vacuum and recall it was at "normal specs".

Post 6- As noted in original post: approx 3,000 mi.(over a three year period - Don't drive much). Did follow a previous suggestion and drove hard 40 mph - 75 mph - accell and decell - twice for a hundred miles each time with no noticeable change in smoke.

Post 7- Am unable to test w/ electric pump only due to engine in process of being torn-down.

Post 8- Cast Iron rings installed by agreement w/ builder, hone grit unknown - Not recorded by builder/ machinist (need to trust work was done as described) - If I get to the point of removing the pistons the rings will be checked. Air temp @ 60 - 75 deg's coolant at 160 to 195 (w/ 190 deg thermo)

Thanks again for the ideas,
paultk

[JoeHall]

What kinda valve guide seals were installed? How about the metal shrouds for the valve seals? Are they installed and positioned properly?

[StudeRich]

When you reassemble it, install the recommended 160 or 180 Degree Thermostat.
In Calif. you do not need the 180 and certainly Not the 195, Never used by Studebaker.

Of course this has nothing to do with the problems.

[altair]

I am thinking maybe an issue with excessive crankcase pressure, you mention PCV and valve cover breathers. I am not conversant with all the various configurations but usually a PVC system would not have valve cover breathers. I have a spare 63 - 259 with a PVC system and there are no valve cover breathers just solid. The plate in front where the oil would have been put in the engine still has the original factory cover. I have no idea how oil was put in this engine other than through the dip stick tube? These could be a mix of parts but for sure some engines had no breathers on the valve covers.

[Jeffry Cassel]

Paul; If all cylinders are involved, it can only be oil getting past oil sweeper rings (were they correctly installed?) or, as noted several times, pulling oil into the carb (pcv valve). Please let us know what you find! If the little umbrellas on the valves were left off, it would have smoked from day 1 and would be obvious.

[jackb]

Funny on that oil fill dilemma. It appears that you have the full flow valve covers but no fill neck and breather. Was there ever a single oil filler on 1 valve cover ? Is that a road draft tube or the PCV piping ?

[altair]

The PVC system appears to be a conversion from where the draft tube was attached, I also have another 63 259 with no draft tube hole just a PVC system welded to the valley cover, and a third with only a draft tube. I wouldn't read too much in to my pictures, the valve covers may be from a different. I was mainly making a point that with a PVC system there would be no breathers in the valve covers. There is also a system where a draft tube is used and on one side has a filtered breather and the other side has a hose connection from the cap into the air filter to collect any crankcase exhaust that may develop at low speed.