The 255 flathead merc in my 49 f2 stakebed has developed a bad problem . It runs ok but showing very low oil pressure when it gets warm . Drained the oil and found coolant in the oil . I would really like to keep this engine . Willing to spend the bucks for a total overhaul , but since I assume this is the result of internal cracks in the engine , can it be repaired ?

 

check your plugs first ,,look to see if one looks cleaner then the rest or if 2 side by side you might have just a blown gasket ..don't figger a catastrophic failure at this point ..a crack in the bore would just need a sleeve at worst ..but I think a gasket is the problem ..let us know what you find..

 

Check the torque on the heads, following the correct pattern.

 

Coolant in the oil is not good for bearings and will result in low oil pressure. Long time use will result in bearing failure. Unless there has been a major event with the engine, over heat or such, I would suspect head gasket failure rather a crack. Torque the heads per specs and monitor the oil for coolant. A tear down may be in your future. Best of luck.

 

I really appreciate the quick responses . I feel a little more optimist about the situation now . Iv'e got alot going on now but will try your suggestions in the next few days . At some point I know this old engine is going to need a complete going over and that is ok . I just want to be able to keep it . Thanks again .

 

we all agreed it could be a head gasket ..so that is good so pull the spark plugs and see if anything sprays when you crank it over ..retorquing a blown gasket won't make it seal better..and head gaskets are cheep and easy to do ..

 

Agreed, but totally blown head gaskets are pretty rare in my experience, on engines with 7:1 compression anyway. Lost torque on a gasket is real common with flatmotors. If torquing reduces or eliminates the problem, I'd still plan on replacing the gasket ASAP, and have the heads checked for flatness.

 

To adress the low oil pressure before you start spending a gob of cash pull the plate from the bottom of your oil pan and clean your oil pump pick up screen.

 

WOW!

 

Concerning the oil pressure , It's fairly decent with a cold engine (about 50 ) . When the engine starts to get warm it drops down in the teens and even lower when idleing . I know some drop is normal but not this much .

 

Sorry to derail, but I guess I picked something up wrong from another thread here..

The 2nd chance garage lists the oil pressure specs at 57 for mine (the 226 I6)
1948 Ford 226 Inline Six Engine Specs

and I too suffer from ~55 when she is ice cold then rapidly dropping off to teens and even down to about 10 when she gets hot at low rpm.

I read somewhere on another thread here at FTE that "any pressure at all" was acceptable as flatties were well known for miserable pressure.

I have some mild blow by and 1 cylinder is low, but no other issues, she purs, no leaks, no fluid mix, oil looks great - no burn/no chunkies/etc.

We'll address my issue in another thread, but I have to ask since it is in the vein here - what do others see for "good" oil pressure on a flattie?

 

First of all, are you going by the dash gauge? They are NOT accurate, particularly if converted to 12v, but even on 6v. Mine will show Zero at idle when fully warmed, which caused me great panic until I hooked up a mechanical gauge and saw that it was 30. When the dash gauge shows 30, it is really 55. I don't know what that "normal" 57 psi really means, probably at cruising speed (2000+ RPM).

Flatheads seem to run fine with very low pressure, but it's not desirable. Oil cools as well as lubes, you need at least 10 "honest" psi at idle. If this engine has been driven much with ethylene glycol antifreeze in the oil, the bearings may already be on their way out. Propylene glycol antifreeze apparently doesn't cause such problems but is hardly acceptable in the oil.

 

just for a reference ..I have a Stewart-Warner pressure gauge ..and it hit's 80 psi cold...warm it is around 55-60 ..and 20-25 at idle ..I run straight 30 weight diesel oil ..with 15-40 I lose 10 to 15 psi all across the scale ..I don't know the history of my motor ..it sat for 15 or 20 years I woke it up with an oil and filter change and had no issues at all with oil pressure...damm lucky I think...

 

An update on my engine block . After checking out several of the suggestions it became obvious it wasn't going to be something simple , So I took the truck into a local repair shop I've used for many years . (Owned by a youngster of 82 ) . He felt it was probably crack in the block around one of the valves , which can be problematic if not impossible to fix . However upon teardown the crack was by a cylinderbore which can be sleeved . I guess under the circumstances thats good news , the old engine was going to need an overhaul at some point anyway . What I found interesting was his decription of a repair process called metal stitching or pinning , which can sometimes be used to repair cracks around the valves . A series of overlapping holes are drilled and tapped in the crack then special screws are put in sealing the crack .He hadn't done it in quite a few years and wasn't real exctted about doing it again as its pretty tedious work . At any rate it won't be necessary unless we find something else . Hope to get the block into a machine shop in Abilene next week .

 

Sounds like you'll be OK with a sleeve! Are you going to do the whole rebuild while you're in there?

If you need a new block let me know. Stitching can be a very satisfactory fix, but cracks to the valve seats are not always worth risking a fix if an alternative is available. Usually only worth trying if you've got a ported block with $$$ already invested.