Need info on 251 engine

[Michel D]

Hello y was checking for some information on full flow filtering for 251 engine.
As you should all ready no the oil pressure relief valve shuts off circulation through the oil filter wen the oil temperature reaches 135°F.

[Wpns 421]

Bonjour Michel Je vois que tu est dans la region de Gatineau moi aussi je suis a Cantley. Je vois que tu connais ton M37 j'ai plusieurs vehicles, si tu serais interesse laisse moi un message et on pourrait se rencontre. Gilles

[Michel D]

Je suis plutot occupé j'ai commencer la restauration d'un M152 en trés mauvais état.J'ai un deuxième M37 qui n'est pas encore fini.
Allor j'ai du pain sur la planche!

[Bob Carriere]

Cut my teeth working on M37, radio and ambulances.....

I am not sure that you can easily convert a 251 to full flow...... having said that with sufficient $$$ and skills anything is possible.. I wonder why you would want to or feel the need to do that..... Oiling and filtration on the Dodge 251 has never been a big problem.. Overrevving and throwing connecting rods is another issue..... and they do run well on 5 cylinders with a gaping hole in the engine block stuffed with rags.

On the oil pressure relief valve..... it is triggered by oil pressure and not by temperature..... in fact 135 degrees for oil temperature would be far too low for a regular gas engine and would result in serious sludge buildup. I would expect the oil temp. to be above the coolant temperature....probably in the mid 250 degrees F at normal operating speed.

I am also in the region.....across the river from Gilles.....across the big river!!
Always available for chats and b-b-b-eers en francais ou en anglais.

Bob C.
Hammond, Ont.

[Michel D]

Thank you for the information!

[Michel D]

Do you think it is a good thing to put some Zinc-plus oil additive in your engine!
The new oil dose not have ZDDP anymore.
I just buy some lucas tb Zinc-plus oil additive to put in my engine i hope this will help!

[Phil Waterman]

Hi Michel

There is a lot of information on web about the need for or no need for zinc additives.

I've asked at the machine shop that has done my engine rebuilds, shop foreman there has something like 30 years experience. His comment was born out by much of the reading I've done, most of the problems he has seen seem to come with high RPM engines with high valve spring loading. In the next breath he said but it couldn't hurt to use a major name brand oil supplement. Which is what I have done.

There are various engines that have had camshaft wear problems, generally poor heat treating, I don't know if Dodge's fall in that group

I guess I would ask my self with the amount we drive MVs we end up changing the oil once at most twice a year, so $10 extra for good oil additive is probably good insurance.

Cheers Phil

[Bob Carriere]

Hi Michel

Much has been written on which oil to use in old engines and it is becoming confusing.

The concern is particularly critical when you have just spent $3000 rebuilding an old engine to factory specifications and you want to protect your investment.

My advice..... why take a chance...?

A freshly rebuilt engine will have a lot of parts that have to "wear in"...such as rings/cylinders..... camshaft lobes/solid lifters.... just to mention the big ones. It seems that most modern "car" oil has been modified to lessen contamination of the environment, lower cost, match closer tolerances of new engines, meet high temperature and high revs.......

Experienced writers have advised that the best oil left on the market for old style rebuilt engines are the oil rated for diesel engines with the possibility of adding the zinc additives. Diesel engine oil is rated for higher friction, temp. and for at least another 2 or 3 years will still have some zinc additives... they are also being phased out apparently. Most new diesel truck...Ford or GM ... will void the factory warranty if you do not use diesel engine oil and opt for the cheaper "car" engine oil......

Stick to known brands.... not the Walmart specials..... use the additives and change the oil Spring and Fall..... even if the engine has not run much over the Winter months..... some of the additives such as anti oxydants will be depleted/exhausted..... and then fresh oil at the end of the Summer season before storing for the Winter.

I initially started my Chev 261 on synthetic but since switched to Rotella diesel engine oil 10w-40...... oil pressure is about 5 pounds higher on the Shell oil compared to the synthetic.....my engine will not run in the Winter and I believe that the Rotella may be better in the long run.

Don't skimp on the oil filter..... cheaper to replace everytime than pay for repairs.

Unless you really abuse you DODGE and pull stumps with it the engine should last you a long time...... just DO NOT OVER REV the engine..... it has long connecting rods that love to fly.... usually through the side of the block.

An M37 or radio truck fully loaded with camping gear, fuel, outboard motor is heavy enough to push the vehcile downhill faster than the engine can hold back and the weight of the truck/cargo will over drive the 251 to destruction... oddly enough driving the truck in low range and revving against the governor does not seem to do as much damage..... at least in my experience it's always been does long down hill runs that have busted up blocks..... besides at 65 mph you can brake only once in a Dodge.... you have brake fade for at least 20 minutes after that....

Fresh HD oil, filters, additives..... and it will drive you to your grave....!

Boob

[maple_leaf_eh]

Originally Posted by Bob Carriere

...

I am also in the region.....across the river from Gilles.....across the big river!!
Always available for chats and b-b-b-eers en francais ou en anglais.

Bob C.
Hammond, Ont.

The important crumb of wisdom to draw from this conversation is there are two sizes of beer bottles sold in Quebec - 'pints' and 'quarts'. Young drinkers' first lesson in applied mathematics is to calculate the percentage of alcohol divided by price per ounce. Growing up in my small town, drinking pints meant you had money to squander to achieve the same buzz.

[Bob Carriere]

Terry..???

Did you swallow the bottle cap?????

Boob

[Michel D]

Do you no were y sould get Cylinder repair sleeve for the 251 engine.
I have a Napa number 2268006 but they don't seem to have it anymore!

[Bob Carriere]

Bonjour Michel

Are you talking about engine cylinder sleeves....? is your engine block that badly damaged....?

I would start with Chrysler of Canada and ask for resleeving parts for a Chrysler Industrial engine.. or if they know who may stioll manufacture them... they were available at one time for most engines but in todays disposable society I think they would be hard to find as a stock item.... a good machine shop could turn the block to accept a hand made sleeve but the cost would be ridiculous......

It may be cheaper to find a replacement engine ........ guy on EBay sells totally rebuilt 251 for about $2300 US dollars......

In fact there are a couple of beat up Dodge radio trucks at a paint ball park near my place that still has the engine block in them.... he might want to sell them

Boob

[Michel D]

No i just need to no if y can have parts for them.

The only one that is damadge is in the M152
The guy was using it to push snow and sand!!!

Now i have a bad oil pressure it start cold at 40 psi and drops wen it
warms up!
But the thing is that the oil pressure is fluctuating

[Wpns 421]

I had the engine in my M37 rebuilt in Hull at a small garage that rebuilds engines. I have all the pistons etc. If you need parts the best place to call is Vintage Power Wagons in the US they have absolutly everything for the Dodges. Yesterday I called them and ordered new spark plugs for the M47 and M43.
In my M series vehicle I use a special oil sold by Stinson Fuels, it is a 15W40 oil designed for older type trucks it is design for older type engines to compensate for higher RPMs while having the viscosity and durability of newer diesel engines. My salesman sold told me this, so I bought a couple cases and use them exclusively on the M37, M43 and especially the Iltis.
Michel j'ai beaucoup de pieces pour ton camion. appel moi si tu as besoin de quelque chose. 819 827 4361 Gilles

[Michel D]

Ok dose some one no what could make the oil pressure on my engine fluctuate 10 to 15 psi!
I no that my gage is ok.
it is not the oil filter.
The oil pressure starts at 45 psi cold and start fluctuating between 35-45 psi. and more the engine warms up the pressure goes down and down!

May be the oil strainer is taking some air!

[Alex Blair (RIP)]

Originally Posted by Michel D

Ok dose some one no what could make the oil pressure on my engine fluctuate 10 to 15 psi!
I no that my gage is ok.
it is not the oil filter.
The oil pressure starts at 45 psi cold and start fluctuating between 35-45 psi. and more the engine warms up the pressure goes down and down!

May be the oil strainer is taking some air!

Micheal..This is normal for the oil pressure to drop back after warming up..
and it will go down after warming up and will fluctuate with changes in RPM..
My old flat heads would start out cold at 40-50 PSI and drop to zero pressure at an idle warm..If it bothers you..put a piece of tape over the gage ..so you can't see it ..Sounds normal to me..

[Michel D]

The problem is the 2 other engine that i have starts up at 45 psi and stays at 40 psi HOT!

[Alex Blair (RIP)]

Originally Posted by Alex Blair

Micheal..This is normal for the oil pressure to drop back after warming up..
and it will go down after warming up and will fluctuate with changes in RPM..
My old flat heads would start out cold at 40-50 PSI and drop to zero pressure at an idle warm..If it bothers you..put a piece of tape over the gage ..so you can't see it ..Sounds normal to me..

Mike..
If you start at 45 PSI cold and you drop off 15 PSI..even 20-25 PSI..that would still be lots of oil pressure..hot..15-25 Psi HOT IS OK..YOUR OTHER TWO ENGINES MUST HAVE BEEN REBUILT AT SOME POINT..

You may want to change your oil over to straight 40 Weight..non detergent oil..That was the summer weight oil that it was designed to use..Multi grade detergent oils were not even invented when that engine was designed..
It wasn't until 1968 that Castrol came out with it's Castrol GTX 20-50Weight multi grade that multigrades came into play..
And then they cut back on the zinc and phosphorous as anti wear additives when the catalytic converters came in so there are a lot of changes in motor oils since the 251CI came into being..Go back to the oil that was designed to run in it and enjoy it..

That is if you drive it only in the summer..you could drive it when it was cold but may have to plug it in to warm the oil before starting..Even with 40 weight ,non detergent oil in it you will see some drop in pressure..
That would quiet your engine,not drop as far on the oil Gage and work OK ..But the engine may be getting a little tired and a new set on main bearings and a regrind on the crank ,if it needs it ..but I wouldn't worry about it and drive it like it was until you decide to rebuild it..
Enjoy it and don't worry about it..
BUT..if it still bothers you..change the oil guage..It is probably worn out and will flicker and vibrate and do all sorts of tricks..it would be my first step ,if it was mine..

[Michel D]

thanks for your help i found out that the oiling system is not the same on this one!

[Bob Carriere]

Bonjour Michel

All oil is thicker when cold and the oil pressure will be high. Once the oil gets hot and thinner and water like it will leak from every bearing on the crank and on the camshaft. You may have just one or two worn bearing but it is enough to drop the oil pressure...... some sludge circulating in the oil system could explain the fluctuation or you have a worn bearing that may be moving...spinning on the lower end of a rod and drip more and somethimes less.

Old M37 would run well on 20 to 25 pounds warm..... below that I would get scared of doing damage.......

If you care about saving the engine before you get real bad damage..... don't drive it..... tear it down before you need a major regrind or score a cylinder wall...... if everything is worn loose you will never find oil thick enough to bring the pressure up......

Parts are readily available check out......www.vintagepowerwagons.com make sure you look at the Canadian 251 engine parts

Another excellent source of information is.....http://www.dodgepowerwagon.com

Like Gilles offered I may also have parts also....... you might be able to get away with just flipping the engine over and doing crank main and rod bearings
....... I even polished cranks by hand with progressively finer emery paper.... not a good job but the darn thing ran good..... they are fairly forgiving compared to modern thight clearance engine.....

Do you have a Dodge military shop manual for the engine..? Dodge flat heads are not hard to work on...... except you have to take the whole darn block to the machine shop to get a valve grind job.

Boob

[Alex Blair (RIP)]

Boob..
You surprised me...
Quote...
"except you have to take the whole darn block to the machine shop to get a valve grind job."
What ever happened to lap sticks..?
Oh,,,I forgot..You were not an old flat head kid..
Jeez..every kid that ever worked on their Fords when I was growing up got a lap stick for their 10th birthday..and a couple of tins of valve grinding compound..coarse and fine..
How else could you do your valves AND get your valve clearance adjustment..??
My machine shop was in my dads garage..

Get your rebuilding stuff here..at least look at it..
http://www.goodson.com/

[Bob Carriere]

Hi Alex

I have found at a farm auction a hand driven device...... almost like a small hand cranked drill...... it holds the rubber cup and when you crank the handle the rubber cup turns about two revs one way lifts automatically ...goes down and turns two revs the other way just like a wooden handled tool..... real neat and twice has fast.

Its called progress......

Try going to local machine shops that sends out most of there work to either Montreal or Toronto and ask for a 3 angled valve job..... watch the look on the kid at the counter!!!!

Boob

[Dave Page]

Hi, if your cold and hot oil pressure is within the normal range but it rises and falls with increasing and decreasing rpms (when hot) that too is normal. However, if the oil pressure fluctuates at a constant rpm, idle or a set rpm, then I would take a look at the pressure relief valve, particularly the spring as it may have lost its set, the ball and seat as either may be pitted, or there may be dirt or sludge in the chamber.
Cheers,
Dave

[Michel D]

This is the problem! (the oil pressure fluctuates at a constant rpm).
But there is one thing that i am wondering on your engine were is connected the oil pipe going TO the filter!

[Bob Carriere]

Bonjour Michel

The oil line that goes to the oil filter has the pressure sensor conencted there..... the line that leaves the bottom of the filter is the return clean oil line to the engine and has even lower pressure.

It could be the electrical connector is contaminated with oil and you have a bad connection.

Have you tried installing a cheap mechanical gauge from Canadian tire.

You just need to instal a tee fitting between the oil line and the filter...connect the mechanical gauge to the tee fitting and you should get a reading that you can compare to the electrical gauge. If you have no knocking sound to the engine the temporary gauge may be a good way to do a test to see if the electrical guage is good.... or you maybe able to remove the existing sensor switch and instal a fitting to connect the mechanical gauge.....

Good luck

Boob

[Michel D]

all ready did it! same thing! the thing is this engine is not connected like yours
the 2 others are connected like yours.
this one is connected near the front of the engine under the alternator!
I would like to no if other pepole are connected like this!

[Bob Carriere]

Hi Michel

I went back to look at your diagram...... are you saying you have an external oil line that runs from the front of the engine,,,,, somewhere behind the big generator.....???

I have never seen that before...... not typical of any Dodge flat head whether it is a 207, 230, 251 or 265.......

Do you have a digital picture of the set up.......must go back to check some books....

Bob C.

[Michel D]

This is the picture!
i think this may be the problem i also have a 237 in a welder and has the same problem!

[Michel D]

I was wondering if the engine bearings and pistons are the same on a
251 1967 wm300 power wagon


Engine parts list:http://www.power-21.com/federalmogul...aspx?pc=Engine

[Michel D]

Well i think this engine will need to be restored!
20w50 seems to be better the pressure is at 25 psi hot!

Dose some body no were y could find a cummins 4bt