Oil pressure or electrical?

Sounds like you inherited someones' headache , that's my thoughts

A bad sending unit is very common on Fords, gas or diesel, you can try changing that first but I think you have a tired engine. Bearing clearances are excessive. Yes it is weird that the radio turns on when you push the glow plug button. A manual radio when turned off stays off. Now if it’s aftermarket system then it’s hard to say what someone has done to the wiring. This sounds like it’s gonna be a budget killer to fix if you can even find parts.

Hey beatupchevy, Why do you participate in this forum if you have nothing helpful to offer?

Answers not posting

I was finally able to speak briefly to the mechanic I brought the truck for an inspection after I purchased it. He says low oil pressure for this engine (1994 7.3L IDI Diesel) is typical, and not to worry about it. I agree that it is probably typical, but not a good thing, so yes, I am worried about it. If this is a tired engine, does the engine just eventually seize up? How do I address the issue, a complete rebuild? I have to use this truck to tow a trailer 2500 miles next month and will probably end up stranded if I don't get this addressed, but I don't have the time or money to rebuild the engine right now. Now I'm stressed out over it, and I will not be returning to this mechanic again because of his behavior and the fact that I don't trust him. I guess I'm wondering if it's ok to drive it short term. When I start the truck, the oil pressure is up where it should be, but once it's warmed up for 10 minutes or so, the pressure drops, but the truck still runs fine.

Thank you for taking the time to reply. This is extremely helpful! I will get the oil pressure sender checked and consider a manual oil pressure gauge. I know the oil was recently changed, so I will pick up a bottle of FR3. I appreciate your advice!

Thanks for the points. I wish you good luck.

Hi, I was the originator of this thread because of my oil pressure issues and glow plug issues. I live in Montana and it has been cold here (last week, overnight highs were near or below zero), so starting can be an issue. Sometimes I find myself waiting until the middle of the day to even try starting my truck, after the temps have warmed up a bit (lucky for me, I am retired, so I have that option). Fortunately, the overnight lows seem to be staying above freezing now and it warmed up to 45 degrees yesterday, and that's when I witnessed nothing short of a miracle after I changed my oil. I'm not entirely sure which oil weight was in the truck, because I haven't had it that long, and should have changed it the oil sooner, but decided to leave the thinner oil in it because of the cold temps (it had a 10 W 30 or a 15 W 40 in it), and I was having a problem with my oil pressure dropping to nothing after the truck was warmed up, probably because of a tired engine (excessive bearing clearances), as you guys told me. My truck has the old 7.3 L IDI Turbo Diesel from 1994, and it calls for regular conventional 30 W oil whenever possible, but switching to a 10 W 30 or 15 W 40 when it gets below freezing. So, I had bought more 15 W 40, cause I was having trouble finding straight 30 W locally. Obviously I was planning to use the 15 W 40 synthetic oil, but then I read this article on oil viscosity (you can read it here if interested - https://ricksfreeautorepairadvice.com/thicker-oil-to-stop-oil- leaks/#:~:text=A%2010W%2D40%20oil%20thins,spaces%20between%20bearing s%20(bearing%20clearances ) and decided I wanted to try the 30 W, and at the last minute, I was able to find some conventional 30 W (Rotella T-1 Straight Grade SAE 30), and it has solved my oil pressure issue, at least for the time being. After I changed the oil, I drove the truck until it was fully warmed up and at idle, my oil pressure stayed up in the normal range, and it has not been doing that recently. Apparently my engine really likes the conventional 30 W oil, and I think this engine was engineered to use it, as opposed to using thinner synthetic oil. I'm not saying I don't still have a tired engine, cause it has 275k on it, but this might keep me in the game for a while longer, cause I need to drive the truck from Butte, MT to Anchorage, AK this summer with a trailer in tow (around 2600 miles), and I am scared to death of breaking down. My next challenge is replacing the glow plugs (and the relay and harness if necessary), because it's pretty obvious to me that they aren't working right, or at least I have no idea what they're doing, with all the clicking on and off of the glow plug system and starting issues. I do have a question for you though, does anyone have a parts list of what we should be carrying in these trucks in case of breaking down? I'm afraid if I break down in the middle of Canada somewhere, then I'll be stuck there for eternity! I definitely plan to carry an extra fuel filter, oil, oil filter, air filter, ect., with me, and an extra battery or something in case I get dead batteries, but what else should I think about taking. You guys are awesome! Thanks for you help, and for listening!

Recommend oil is Diesel approved 15W40 oil. So if the straight 30 weight now gives you oil pressure that is a sure sign of worn engine bearings, I don’t think I would trust it to make that journey your planning, it could leave you walking. The glow system cycling means that there are open glow plugs or a bad circuit assembly under the valve covers. Only way to find out is to open it up and start checking the ohms of the circuits and the glow plugs.

Thank you! I'm going off a manual that was written over 30 years ago, so maybe back then, 30 W oil was preferred for this engine, cause it clearly states that 30 W is preferred, but if temps drop to freezing, then switch to 15 W 40 until it warms up, and then back to straight 30. Perhaps with the evolution of all these synthetic oils, 15 W 40 is now recommended, but I'm loving my oil pressure with 30 W. Thank you for your comment about breaking down and having to walk! I am not going to risk it unless I get this truck running really good, and have it checked over by a real mechanic, because they seem to be in short supply where I live. I do know some in a neighboring city where I used to live, so I should be able to get one of them to help me, but I want to be as independent as possible, so I can address minor common issues as they come up, especially while travelling. Best regards!

BTW, I found a supplement for the 7.3L IDI Diesel in my truck, and it provides easy to follow instructions (which I desperately need) for checking, repairing, and replacing the glow plug system, including the controller, the harness, and the plugs. I find many You-tube videos on the topic to be confusing (well, many of them are confusing and some of them are just flat out wrong), but I know there are some good one's too. In any case, after watching videos, I wasn't sure I wanted to attempt the glow plugs, but come to find out, it ain't that hard after all. Thanks to this forum for the encouragement it provides!

Yes some of the you tube videos are bad but some are very good. Diesel specialist is what you need not some gas guy that says he can work on diesels. Check reviews of shops in your area.