Hello all, New member and proud 1946 ford pickup owner. I'm wondering if anyone has had problems with their flathead oil pressure being too high after about 10 minutes of driving and subsequently the engine getting too hot. Any leads or ideas are much appreciated. This is my first adventure into vehicle mechanics and maintenance. Last weekend: -changed the drums to discs -changed the oil with: zinc + straight 40. -installed thermostats in radiator hose necks. Thanks -KYLE
Pressure relief valve may be stuck. Depending on which flathead you have, the pressure relief will be on the pump or in the valley under the intake manifold. It could have both if it is an early engine with a later oil pump installed. Regarding the overheating, make sure that you thermostats have not moved in the hoses. They normally need to be constrained in some fashion. Also, make sure your new brakes are not dragging. You need to have different residual pressure valve for disc rather than drum brakes.
Was the oil pressure too high before you changed it? About the temp,,,,is it really too hot,,,or maybe a gauge problem Are these factory gauges or aftermarket electric? The stats in the hoses might be the problem,,,especially being you just did all this work. Tommy
It steadily climbs and then is pegged past 50 Deg. if driven for more than 15min. Since the gauges are original and the gas and speedometer are not functioning, my hope is that the gauge is inaccurate. Other than replacing with new gauges, I have no idea where to begin looking.
engine is 239ci Fritz jr, thanks for the advice on the brakes, I don't think they are dragging, however I'm not sure what "different residual pressure valve" entails. All I did was the front disc conversions and replaced the brake lines with 3/16 and left the 1/4's on the rear drums. I'll look at the thermostat positioning but I don't think they could possibly move how I restrained them. Tommy, the oil pressure and heating issue was exactly the same before thermostat install and oil change. The engine behavior has not changed except it now starts like a brand new engine.
So what is the actual oil pressure, and what is the coolant temp? "Too high" & "too hot" are not technical terms and don't help people who are trying to help you.
Blues, Thanks for the feedback, I have been using trial and error + reading a ton, because I have never worked on a vehicle before this one. The oil pressure gauge goes from 0-20-50 and it is pegged past 50 after a short drive. I'm not sure how to measure the coolant temp after running-the gauge just rests on H. Both the oil and temp gauge both steadily climb as I drive.
Thanks Tommy, Thats just a stock photo ha, but mine is almost identical. I'm excited to put a picture up with the custom canvas campershell we built. My fiance and I are going to sell flowers out of it on the weekends.
I have never heard of an oil pressure issue that’s just steadily increases as you drive. Man,,that Is a new one for me. The same for the temp,,,yes,,,I have had vehicles get hotter as they are driven,,,but,,,I always knew that they were definitely hot. At least you are trying to learn and work on it yourself,,,congratulations on that! I am not sure about these old gauges,,,are they mechanical or electric,,,surely someone on here knows. Good luck Kyle. Tommy
I should have asked: Is your truck still 6v? Or converted to 12? If 12, some resistors used for this may drift when hot.
Ah, Ken, I understand your question a little more now. The system is original 6v and the gauges are also original.
So I would say that both gauges need to be confirmed to be accurate. I understand it's your first experience dealing with this, so I'll try to help. Checking and comparing the readings of those gauges to known good gauges is really the only way to confirm their accuracy. I would suggest considering adding a supplementary 3 gauge under dash panel, using oil pressure and 2 water temp gauges (one for ea head). My preference is for mechanical gauges, at least with the oil pressure, but I prefer them vs electric gauges for coolant temp as well. But I understand that get a little expensive as well. So, I'd get a good mechanical oil pressure gauge anyway, and if you can't swing 2 new mechanical coolant gauges now than an inexpensive temp gun to check the coolant temperature at various points on the cooling system would be a practical approach to solving this. Gauges can get expensive, here's one that not too bad, and it looks decent as well. Cheaper than repairing a failed engine because of lube oil supply issues. https://www.amazon.com/Mechanical-P...ssure+gauge+mechanical&qid=1571954270&sr=8-39 Here's an inexpensive infrared temp gun with laser pointer, not a bad tool to have for any auto enthusiast, more so for a flathead owner: https://www.harborfreight.com/121-infrared-laser-thermometer-63985.html Once you verify actual pressures and temps, than you can take steps to address. My advice is to confirm what you have first. Very important.
My '40 Ford pickup uses stock gauges . They have been converted to 12 volt operation with an appropriate resistor. The oil gauge acted funny and scared me and the temperature gauge also seemed off so I added mechanical oil and temp. gauges. Quite a difference! I suggest that you consider adding mechanical gauges to be sure you are getting an accurate reading.
Thanks for the advice guys, I will look into installing mechanical gauges but the temp gun sounds like a great starting point.
Your oil pressure sender on the back of the block could be the problem.You might also want to go on www.fordbarn.Its the sister site to this.
Did the oil pressure issue occur just after replacing the cam bearings? Those flatty's had some strange cam bearing- oil pressure issues.
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