I have a 2001 Dodge with a Cummins and the other day my oil pressure guage dropped instantly to zero. I talked with the local dealer and was informed that it was my oil sending unit that was the problem. I changed the sender and the problem remained the same. I do however have intermitant oil pressure reading on my gauge but this lasts only seconds...HELP!

 

Next oil change I would add some Marvel Mystery to the crankcase. Could be some sludge build-up. Are you regularly changing the oil and the filter?

 

What oil do you use? Did you purchase the truck new? If not, and you started using synthetic oil when the previous owners used regular oil, it could be the cause. Synthetic oil will clean your engine out, and all that crusty carbon will fall down in your oil pan. Just like when you use an engine restorer. You most likely have carbon or other trash clogging up the screen on your oil pump. This would typically only happen when your truck has been running a little while. As the truck sits, over night or during the day all that junk falls off that screen. I've seen this scenario many times.

 

Synthetic is not going to clean out an engine which has been neglected. Carbon can be almost impossible to clean out. My dad is rebuilding his 1985 Dodge Diplomat from the ground up (don't ask) and has shown me the heads from the 5.2L (the father of our Magnum engines), which he had magnafluxed and tanked. The passages still had caked on carbon, which he has had to use a drill and even porting tools to remove.

 

Just sharing what I have learned and found in my days at work. You can chose to believe it or not. But I don't make stuff up. Using synthetic oil after long usage of regular oil can and will cleanse your engine.

 

I did not say you are making anything up, but you are incorrect in stating that synthetic oil is going to clean up an engine and remove carbon deposits. If you look at my engine building threads, you will see that my engine was badly neglected before I bought the truck. I had also encountered the same situation with an old S10 Blazer. The engines were so thoroughly coated with grime and carbon that there was only one way to clean them out, and that was with old fashioned hard work.

Bear in mind that "dinosaur oil" is not bad for an engine. It is the lack of proper maintenance, that kills the engine. Since I have rebuilt my engine, I started running synthetic oil, because I wanted to stretch out the intervals for changing the oil as I drive a lot of highway miles. Over time, oil breaks down and starts to leave carbon deposits due to heat and frictions. Since cast iron is porous, this is the perfect environment for carbon to attach and never leave, unless forced out.

If you think that an oil passage, that has been packed with carbon, will be cleaned out by using synthetic oil, then you are sadly mistaken.

 

Well I guess all my years in the automotive repair world and tech school have all be a waste of time. Thanks for setting me straight VW.

 

[sm=bicker.gif]

 

Yes. If the school taught you that synthetic oil will clean out carbon (including blocked passages, as I pointed out above), then that's a **** poor school. Seems to me you didn't read a word of what I wrote above.

Please explain how synthetic oil would have cleared out BAKED ON carbon deposits that had the oil passages clogged. I can't wait to read what you have to say. [sm=GrowUp.gif]

 

carbon deposits occur in the combustion chamber and on top of the pistons. oil is not present in that area so it will not clean carbon deposits at all. Synthetic oils will clean the inside of the motors however, seen it 1st hand years back when I had a honda prelude. Doing a valve adjustment, the area under the valve cover was a nasty black much like Gary's valley area under his intake manifold. Switched to Castrol Synthetic (when it was a sythetic) and by the next valve adjustment thearea underthe valve cover had a light brown coating now instead of the nasty black. I was amazed by it and never went back to dino oils... Since switching to synths, I have not had 1 single internal engine failure due to oil or any crap left over from the previous owner. all of my rides get synth on their 1st oil change and I never look back. Doesnt matter how many miles are on it, plus I have never had an oil leak after switching over to synthics. This coming from a guy who has poked his head in every motor I've owned since the mid 80's. IMO running synthetics will clean your motor. maybe not as fast as using an additive but it will clean it. as far as junk falling into the pan and getting sucked up into the screen... I've never seen or heard of that one so I cant comment on it.