Squirlye Posted December 27, 2022 Share Posted December 27, 2022 Hey guys I'm back, it's been awhile since I've posted about my 86 F-150. Im now driving it almost daily. I went ahead and installed the HEI distributer, it was a piece of cake. I put in the aftermarket tach at the same time. Everything works great except the bulb burned out after about a week. No tach at night, no biggie I just shift by ear anyway. I bought a complete window and door seal kit (Fairchild) from rock auto. It definitely was worth every penny. Now the windows don't rattle when I'm driving on those bumpy ole Arizona roads. It's also a whole lot quieter inside. I also picked up a Taurus alternator and exhaust manifolds from a 90 F-150 300 Il6 from the local pull n save. Those 2 will be by next install when I have the down time time. I've been busier than a one armed pin setter lol. I've got big plans for this truck so I will be posting my questions and ideas in the near future. I do have a few quirks going on as well. It gets hot when I go down the freeway after about 10 miles. Not sure why, changed out the thermostat when I first got it. No leaks anywhere and the heater works great. I'm wondering if the water pump is going bad, but like I said no leaks anywhere. Also when I'm in 4th gear it bucks if I'm under 2000 rpm. Not sure what the gear ratio is in the transmission. But it seems like a big jump between 3rd and 4th gear. It pulls really good from 2nd to 3rd. It has a granny for 1st gear and I never really use it. So that's what's going on with me, thanks for all of your future help. Link to comment Share on other sites More sharing options...
Gary Lewis Posted December 27, 2022 Share Posted December 27, 2022 Welcome back! Glad the window & door seal kit helped. They make a huge difference. Frequently when an engine overheats when going down the highway but not in town it is due to a head gasket leaking. Hope that's not the problem with your truck, but water pumps don't usually get tired. They normally fail by the bearing or seal going out and you have a leak. So I doubt it is the water pump. Link to comment Share on other sites More sharing options...
salans7 Posted December 27, 2022 Share Posted December 27, 2022 Welcome back! Glad the window & door seal kit helped. They make a huge difference. Frequently when an engine overheats when going down the highway but not in town it is due to a head gasket leaking. Hope that's not the problem with your truck, but water pumps don't usually get tired. They normally fail by the bearing or seal going out and you have a leak. So I doubt it is the water pump. A wise man once said: "Putting a glove over the radiator cap opening will tell you if there's combustion in the cooling system. White smoke from the exhaust will tell you if there's coolant in the combustion system. " Link to comment Share on other sites More sharing options...
grumpin Posted December 27, 2022 Share Posted December 27, 2022 My old truck did that. Good temps around town and on the flats, but would get pretty warm climbing the passes. I put in a Champion 3 row aluminum radiator. Did the trick. Link to comment Share on other sites More sharing options...
1986F150Six Posted December 27, 2022 Share Posted December 27, 2022 My old truck did that. Good temps around town and on the flats, but would get pretty warm climbing the passes. I put in a Champion 3 row aluminum radiator. Did the trick. Sometimes a replacement lower radiator hose will not have the internal coiled spring and at sustained speeds, the hose may collapse and restrict coolant flow. The 1986 4.9L if not modified will be computer controlled. This system can cause running issues if one or more sensors is missing or if a vacuum leak exists. This same condition will make for poor gas mileage. How is your idle? Link to comment Share on other sites More sharing options...
Squirlye Posted December 28, 2022 Author Share Posted December 28, 2022 Sometimes a replacement lower radiator hose will not have the internal coiled spring and at sustained speeds, the hose may collapse and restrict coolant flow. The 1986 4.9L if not modified will be computer controlled. This system can cause running issues if one or more sensors is missing or if a vacuum leak exists. This same condition will make for poor gas mileage. How is your idle? I will have to check the radiator hose to see if the spring is there. It idles good but not smooth. Plug #5 is a bit oil fouled. I'm pretty sure it has a bad valve seal. It only smokes at start up and when idling. It starts up just as good as my 96 Mustang. Except in the cold mornings, the choke doesn't work. I think that it needs to be messed with. As soon as I get in my truck after work it fires up immediately. And I'm sure I have a few vacuum leak's somewhere. But on the other hand I get almost 14 mpg. Go figure that, at our work we have a 2017 F-150 eco-boast that is only getting 16.3 mpg. This is a work in progress, I'm enjoying the tinkering for now lol... Link to comment Share on other sites More sharing options...
1986F150Six Posted December 28, 2022 Share Posted December 28, 2022 I will have to check the radiator hose to see if the spring is there. It idles good but not smooth. Plug #5 is a bit oil fouled. I'm pretty sure it has a bad valve seal. It only smokes at start up and when idling. It starts up just as good as my 96 Mustang. Except in the cold mornings, the choke doesn't work. I think that it needs to be messed with. As soon as I get in my truck after work it fires up immediately. And I'm sure I have a few vacuum leak's somewhere. But on the other hand I get almost 14 mpg. Go figure that, at our work we have a 2017 F-150 eco-boast that is only getting 16.3 mpg. This is a work in progress, I'm enjoying the tinkering for now lol... https://www.ford-trucks.com/forums/1110073-choke-adjustment-101-a.html https://www.ford-trucks.com/forums/1325963-gas-mileage-recipe-4-9l-300-a.html Link to comment Share on other sites More sharing options...
1986F150Six Posted December 28, 2022 Share Posted December 28, 2022 https://www.ford-trucks.com/forums/1110073-choke-adjustment-101-a.html https://www.ford-trucks.com/forums/1325963-gas-mileage-recipe-4-9l-300-a.html 1984 F150 with 4.9L engine [feedback system still operative]. This is my son's truck and he is out of the country, so I have had time to work on this as time permits. The engine was idling @ 950 - 1050 RPMs and was not smooth. At this idle speed, which remained the same even with the idle screw all the way out to the point that it was not touching the throttle body, the vacuum was 18 1/2" Hg. My 1986 F150 with 4.9L engine and Duraspark conversion pulls 21 1/2". The idle air fuel mixture screw had to be turned out ~5 turns for best idle. Much time has been spent searching for the cause. All vacuum hoses, intake manifold junction, carburetor base and EGR adapter have been sprayed with copious amounts of carburetor cleaner without revealing the leak. Sometimes, when spraying near the #4/5 cylinder intake manifold junction, I thought I could detect a slight variation in engine speed and also when spraying near the carburetor base on the firewall side, but when repeated, the change would not repeat? All vacuum hoses have been pinched close with no change to engine speed. The EGR valve has been temporarily blocked and this did not solve the issue. I have done the "jiggle" test to the wiring harness and nothing showed up. Not only did the engine not idle well, it missed @ ~1250 RPMs when under a very light load and bucked when decelerating. I have posted and asked questions of forum members, respected local technicians as well as retired engineers and had not found the answer, until this past weekend. After an Internet search, I found on Youtube where a professional automotive technician asked the question, "do you have a high rough idle?" and proceeded to tell that he had a smoke generating machine which he used in searching for vacuum leaks. He is quite good and showed how a Do-It-Yourselfer could duplicate this quickly and inexpensively, so I did and was absolutely amazed how quickly and easily done. I purchased a $0.69 cigar! With the engine off, I taped the mouth of the carburetor with duct tape. I then took the vacuum hose which normally supplied vacuum to the temperature sensor on the air cleaner, which was available since the air cleaner was off. I lit that "bad boy" and after taking a deep draw, blew into the vacuum hose. I placed my thumb over the vacuum hose and took another deep draw and blew into the vacuum line. With the 2nd attempt [very quick], smoke was evident in a place I did not know existed. On the intake manifold is what I call a vacuum tree [distributor?] which Ford used on all 4.9L engines. Depending on the trim packages, options, etc. some, but not all ports are used. The remaining ports are capped with rubber boots. Also, keep in mind that since this vacuum distributor [tree?] is threaded in, the ports may be oriented differently. WELL, there is one unused port nearest the engine block, which in this case, is pointed downward, nearer the exhaust manifold. As a result of its location, the 34 year old rubber cap has been exposed to much heat and had dried out. The end of the cap was missing and the hole is about 1/2 - 2/3 the size of a pencil eraser. Do you think that could cause the previously described symptoms??? Due to the location, which cannot be seen due to the myriad of vacuum hoses, etc., the typical "hiss" could not be heard since the port was facing downward and in the vicinity of the exhaust manifold. Nor could it be "hit" with the copious amounts of spray. Occasionally, as I sprayed the intake manifold joint near the #3-4 cylinders, I thought I could detect a difference as well as when I sprayed the carburetor base and EGR adapter area, but could not get a repeat when I tried again. In hindsight, what was happening was at some times, the angle was just right and some vapor must have reached the open port. I carefully used a screwdriver and removed the hardened residue and replaced the cap with one "I just happened to have" [thank you, Lord!]. I then repeated the smoke test and no other leaks were detected. After removing the duct tape from the carburetor opening, the engine leapt to life at a rather steady 450 RPMs [compared to rough 950 - 1050 RPMs]. The idle screw, which had been loosened to a point that the screw did not even touch the body, had to be turned many times just to raise the idle to ~650 RPMs. I then adjusted the idle air fuel screw which had to be turned in about 2 turns, and left as is. The idle vacuum, which had been ~18 1/2" now is 21 1/2". This morning, I drove it to work [~13 miles] and it is one happy engine with no missing or bucking! Gary LewisReply | Threaded | More Link to comment Share on other sites More sharing options...
mat in tn Posted December 28, 2022 Share Posted December 28, 2022 I will have to check the radiator hose to see if the spring is there. It idles good but not smooth. Plug #5 is a bit oil fouled. I'm pretty sure it has a bad valve seal. It only smokes at start up and when idling. It starts up just as good as my 96 Mustang. Except in the cold mornings, the choke doesn't work. I think that it needs to be messed with. As soon as I get in my truck after work it fires up immediately. And I'm sure I have a few vacuum leak's somewhere. But on the other hand I get almost 14 mpg. Go figure that, at our work we have a 2017 F-150 eco-boast that is only getting 16.3 mpg. This is a work in progress, I'm enjoying the tinkering for now lol... when you consider the fuel mileage alone it could mean a slight vacuum leak and going over hoses and gaskets could smooth these out. however, there are dozens of possible sources for unmetered air as the hvac system is engine vacuum operated as is the power braking and even the automatic transmissions. it is not as daunting to narrow down as it may seem. just a matter of doing one step at a time. but 14 means it's very good. certainly not falling apart. as to mpg of the newer trucks. it is very disappointing really as how little progress has been made in thirty years given the technology, engineering, computer-controlled management systems, and let's not even get into the expense of all of this "progress". the power and drivability and comfort are there but that is trying to make up for the lack of work performed. 100k to have some other company's brand name on my truck seems a bit silly to me. certainly not something to feel superior about. Link to comment Share on other sites More sharing options...
1986F150Six Posted December 28, 2022 Share Posted December 28, 2022 when you consider the fuel mileage alone it could mean a slight vacuum leak and going over hoses and gaskets could smooth these out. however, there are dozens of possible sources for unmetered air as the hvac system is engine vacuum operated as is the power braking and even the automatic transmissions. it is not as daunting to narrow down as it may seem. just a matter of doing one step at a time. but 14 means it's very good. certainly not falling apart. as to mpg of the newer trucks. it is very disappointing really as how little progress has been made in thirty years given the technology, engineering, computer-controlled management systems, and let's not even get into the expense of all of this "progress". the power and drivability and comfort are there but that is trying to make up for the lack of work performed. 100k to have some other company's brand name on my truck seems a bit silly to me. certainly not something to feel superior about. I agree that fuel mileage has improved very little, but then I am reminded that my 1986 F150 with 4.9L engine which could achieve 25+ MPG on the highway weighed ~3750#. Today, a F150 weighs 5000+# with much more power. I would like to have a 2.7L Ecoboost in a 3750# truck and see what gas mileage that would return. Link to comment Share on other sites More sharing options...
Recommended Posts