[Yoder]

i have a 79 bronco with a 351m and when its cold it has great oil pressure about 75 but after it warms up to 200 degrees it looses oil pressure to about 25 or less y is this?

[Johnny Reb]

Yoder, on Feb 9 2009, 07:13 AM, said:

i have a 79 bronco with a 351m and when its cold it has great oil pressure about 75 but after it warms up to 200 degrees it looses oil pressure to about 25 or less y is this?

time for a overhaul soon. The bearings are getting worn out. I had a 351 in mine. I put new bearing in it and it ran real guiet--then it would start chattering-then get quiet . I was gonna put them in myself ,but this guy jumped the gun on me and put them in and it pissed me off. So I drove it home parked it, got a 390 and drooped it it. , and I have lived happily ever after. If you have someone doing the work. Make sure they do it right and keep a receipt. Some of the garages will definetly rip you off. Once you take a interest in working on your bronco-you will do the work yourself and know what to do. I ma sure you will catch on fast. Good luck.

[Seabronc]

I've got the same issue, but I have been nursing it along for 2 years now since the engine still runs strong. Last year I was successful with running 20W50 with a quart or two of Lukas all year, but this year it has been quite a bit colder so I'm using 10W40 with Lukas. A good rule of thumb is 10 lbs per 1000 RPM and everything will be fine. I get around 25 lb at 650 RPM and 40 lbs at cruise. As long as you don't hear any associated knocking you should be fine for a while. Like Johny Reb said you are close to a rebuild but you can nurse it along until you are ready to bite the bullet and go for a short block, long block or rebuild it yourself.

Good luck,

[Yoder]

ok that was wat i was thinkin thanks alot to all

[79fordblake]

You still have plenty of life in your 351, but yes your bearings are worn and it would be a good idea to install new ones. A friend of mine has a 79 Bronco with a 351 and it holds about 7psi or a little less at hot idle, still runs good and runs quiet, no smoke and it still gets hammered daily. May not be smart but it shows the durability of these engines even with very high milage. They say built Ford tough for a reason

[Johnny Reb]

79fordblake, on Feb 17 2009, 07:05 PM, said:

You still have plenty of life in your 351, but yes your bearings are worn and it would be a good idea to install new ones. A friend of mine has a 79 Bronco with a 351 and it holds about 7psi or a little less at hot idle, still runs good and runs quiet, no smoke and it still gets hammered daily. May not be smart but it shows the durability of these engines even with very high milage. They say built Ford tough for a reason

That may be true,but sometimes it pays to fix before getting stranded in a bad place. I wouldn,t want to chance mine 30 miles out in the mountains or in heavy traffic when the engine decided to blow . One of mine ,that has the 400 is guiet ,has plenty of power,but the oil pressuer drops alot when it gets warmed.I will re-build it this summer. I myself rebuilt a 390 in my brothers Ford pick-up. It ran quiet, had plenty of power ,but did have high mileage and was leaking oil in numereous places. He drove it in from almost St.Louise . When I tore the engine down. It had 1 (ONE) tooth on the timeing gear and I think 3 rods-had the caps loose on them-I took them off without a wrench. I also put in a timeieng chain on my old ford 292 because it was looseing power. When I got the new chain on and started it up. It sounded like about 6 rods came loose. I re-built that engine -instead of takeing a chance of blowing the block to pieces and it is still running. Oh-it had 285,000 miles on it -never used oil or had never been taken apart--yes Ford made good engines-like alot of makes-and alot of good use comes with maintances. So, think about the conciquences . It could be putting your life or someones elses at risk.Thanks

[79fordblake]

I wasnt meaning he should continue to run it the way it is. Just thought he should know it will more than likely still serve many more years the way it is. Alot of people don't like the 351m/400 so there are lots of block to still be got out of junkyards so its not really a big deal if you blow one up. Im not saying go blow it up though, I treat the 400 in my 79 Bronco like a baby, keep it full of coolant, keep oil and filter changed on schedule, and add a quart of Lucas oil stabilizer everytime I change the oil. I would drive it anywhere if I had to.


My friend on the other hand barely changes or checks oil, hardly ever checks coolant, but the ole 351m is still hanging in there. He isn't very mechanically inclined though so he pretty much ignores the mechanical guages he had me install for him.