Hello Guys, Intro--> I bought a 94 F-150 5spd 190k miles and this thing run like it was new,unbelievable great.Then one day while on the interstate,,Temp sending unit,H2O pump,thermostat failure seemed to be all three (point is I didnt see or notice it till I was on the off ramp and smelled a hint of burnt oil and noticed the steam from hood It got really HOT)... I did the repairs fired it up , it run like is has water in the fuel,, so I did a compression test all cyl. got 120lbs and held it, I did have a burp and bubbling in radiator,,so I tore it down to find cracked head in #3, nothing else looked bad, cyl walls looked good didnt see any cracks any place in the block,,so I proceded, done and back together it still runs funky,like when im cruiseing down the interstate it feels like a trailor hitching effect or light chugging also when im putting around in a higher gear and should really be in a lower gear foot off or barely on the throttle I notice a slight chug. Fortunatly I was able to drive this truck for a few months before the heatup thing, or this could almost go undetected, I think it has to be related to the over temp,what could it be? No engine light or code diag, doesnt seem to change from cold to hot engine temp Thnx for any suggestions or solutions... Mike

 

Welcome to FTE Mike. Are you saying that you put the head back on with it still cracked? I couldn't follow completely.

 

Sounds like a bit of surging, perhaps a vacuum leak, possibly confined to one or two cylinders. This is EFI, OBDI, right? Got any check engine light action?

Do the WD-40 or other fine brand spray product test. With the engine at idle, spray around gasket areas and listen for any change in the way the engine runs.

Better minds will chime in.

(You didn't really put that head back on, I just knows it. But what did you put back on?)

 

Thnx for the welcome,,haha you know'd it right ,Sorry I wasnt more clear But the head is new,and a gasket kit everything but the gear cover was put on,and no engine light what so ever,, but then again I didnt see one when it over heated either and i should have seen something in the form of a light right?b ut that is minor for now i what this thing to run like i did when i got itim sure it will.. thnx

 

How is your emissions equipment?

Check the vacume lines near the EGR line. Spent nearly $500 replacing everything from the termactor to the egr valve/sensor/solenoid trying to clear codes when it was the three vac lines near the egr line had fused together. My truck did similar things when that occurred.

Also re-run those compression tests on all cylinders or trip the computer into a cylinder balance test mode. The comp should be able to give you which cylinder that is not contributing as much as the rest and a "best guess" for a reason why. A cylinder compression test is much quicker and uses no gas. If the low spec is 75% of your highest reading (only on this motor folks) then your still fine. If below that then you have some problems.

 

Ok Battlemaster I'll try that,,It must be something simple like this and from a heat issue, tomorrow I will open up that black flexible conduit and look..Hmm how do I do the comp thing? or could you point me to a place to find out,, with any luck at all I will not need to do that. haha thnx guys

 

Your probably going to need a code reader for that. Or the low tech solution is to pull plug wires while the engine is running and have someone keep an eye on the tach. Takes about five min a pop to run the test. Have to run the test up to three times to test for the severity of the issue. It's not going to resolve any issues but it will indicate if thats an issue or not.

Also noted that you mentioned the #3 cylinder. Thats my low cylinder and also seems to be the cylinder most brought up by others when they are having issues. Or it could be coincidence. If it isn't I wonder why that cylinder seems to crap out more than the others.

Also check the heat shield if you have EFI. Seems to be Fords solution to placing the fuel rail in close proximity to the exhaust manifolds. Check the pressure going to the rail. Might be that the booster pump is inoperable ,or like in my case, just doesn't exist. Guess Ford decided that the booster pump wasn't needed along with the solenoid to switch between tanks which lead to my truck swapping fuel between tanks and vapor lock issues in city traffic.

 

Ok well I did some checking and found no vacume leaks,the egr seems to be in good shape no leaks and moves. Im going to replace the tps today in hope that it might be this simple...Also I replaced the coolant sensor(the one at the thermostat houseing) and this did nothing to the gauge in the dash?(it still dont work) I found out there is a temp sensor which is different from the coolant sensor. I think its at the back of the motor on the passenger side,, there is also 2 other sensors on the drivers side one about midway which I assume is oil sending unit,, the other one is on the same side but to the rear of the engine which im not sure what it is?? Also I have no engine warning lights what so ever, with the ignition on before start there is no lights? there is the alt warning light that works and abs light checked all the fuse's and breakers but no luck finding anything obvious.. This engine runs awesome I got 41 miles out of 2.2 gallons of gas 22 miles of that was on the interstate the rest was in town normal driving,, with power up the yang I have no problem running 70 mph barely touching the throttle and with plenty of power left to pass like a cheeta!!....@Battlemaster everything is on the engine as it was from the factory, like the heat sheild ect. So I may tinker a bit replaceing some of the inexpensive stuff and may just have to drive it till what ever it is becomes so bad that its obvious what it is,, as long as it wont do harm. But as many posters dont do, I will keep replying with updates and make that final post as to what fixed it when the time comes..Thnx Guys and Keep on Trucking!!

 

Also I wanted to add the the original HeadGasket I removed the water jacket holes were 99.9% clogged to the #3 cyl and the rest was about 80% clogged along the rest of the cylinders the ones at the front and rear of the engine were not near as bad but still showing some signs of clogging,, I made the holes in the new gasket about 5/16" they were only about 1/8" new.. I had bought the cheaper head gasket kit dunno if this is why, but I had noticed that the superduty E series head gasket had much bigger holes in the water passage FYI..