Need info on 251 engine

Bob Carriere · #1 29-01-10, 21:57

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 · #2 03-02-10, 15:09

Thank you for the information!

Michel D · #3 23-02-10, 16:19

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 · #4 24-02-10, 01:13

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 · #5 24-02-10, 02:40

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 · #6 24-02-10, 03:46

Quote:

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 · #7 24-02-10, 04:43

Terry..???

Did you swallow the bottle cap?????

Boob

Michel D · #8 03-03-10, 01:28

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 · #9 04-03-10, 03:34

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 · #10 04-03-10, 04:17

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 · #11 04-03-10, 11:57

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