302 header blow off/dead engine

[Iceman21]

Hey I just got a 81 f-150 with a 89 mustang cobra 302 gt engine swap in it, it was mean as hell on the way home, however it did have a header leak (missing two bolts) no big deal right, just some loud clickin? WRONG. The header managed to blow off on that end and slowly kill the engine... No power... No torque... If I put my foot in it just died. Anyway how bad the engine can get messed up from that, and if I get a new gasket and bolt the header back on, will my problem be solved?

 

[--weezl--]

first, this really isn't the right forum for your question, your truck, nor the motor that has been put in it is ranger related... BUT, to answer your question, you can mess a motor up fairly bad by that.

before i explain what can happen with headers blowing off, i doubt that is your problem, it sounds like your motor is blown, and the guy you bought it off of made it work for now, and took those bolts out to make it seem like that's the problem...

the way the 89 mustang motors work (gt motor is the same as the LX motor) they area MAF motor, which use 4? o2 sensors, the o2 sensors would be out, due to the exhaust leak, however, they will go into a default setting if they read way out, and the engine will still run just fine... the header being off, the motor will run fine, until something goes wrong, then it probably won't run at all...

what CAN happen, your header should provide a small amount of back pressure, this slows down the exhaust coming out of the cylinder, without this backpressure, hopefully nothing goes wrong, and it will be fine, obviously louder, might have a LITTLE less power (if you've never driven this truck before, you wouldn't notice the drop) however, without backpressure the exhaust comes rushing past the exhaust valve, and acts like a blow torch, with the speed it comes out, this CAN burn a hole in the side of the valve, which will make that cylinder drop out completely. if this happens on all 4 cylinders on that bank, i doubt the motor will even run. if this is the case, you're looking at a top end rebuild, you will need, intake manafold gasgets (upper and lower) throttle body gasket, head gasket(s) even if the issue is only on one side, i HIGHLY recommend doing the other head gasket at the same time... new valve(s) recommend replacing any valve springs that test out of spec, and all valve seals

i would also suggest having a machine shop check the heads for cracks and warping, and plane them if necessary. when I did my heads on my mustang, both were out of spec by 0.002-0.004" if this is over looked and they are even just a little warped, you may be replacing the head gasket again in a month or two...

end of story, I hope you didn't spend a whole lot on this truck...

 

[Iceman21]

I posted in this forum to get an answer like that one, I know it isn't an rbv but i needed help.

Going out to look at it in the daylight, I notice the front two bolts are backed out, so the header isn't actually blown off, just loose. In the front.

Tested the battery and it's also low, so I'm hoping that the combo of a loose header and bad spark from the low battery is the problem. When the engine started it sounded perfect nothing out of the ordinary, and it had a plethora of power, then I mean it was all of a sudden gone... But after It went to hell it didn't over heat so I'm hoping all is ok!

The only thing I paid for this truck was gas to get it home!

 

[Surrey]

The only thing I paid for this truck was gas to get it home!

Well thats a good thing. Wish I could get a free 302...

 

[Andy D]

How much trouble would it be to do a compression check? That will pin point any damage. Maybe it wont be as bad as it could be. A freebie is bound to have a bunch of faults Especially a hacked motor swap.

 

[Iceman21]

I think the compression is good because I can still bumpstart it

 

[Iceman21]

And it will hold on a slope in gear.. And i dont know how to test it!

 

[Iceman21]

Could the backed off header bolts cause a vacuum that would cause the 02 sensors to kick off and the fuel air mix to be off? She'll idle just fine but the second I go to push the throttle it chokes, battery may be low also. I'm just throwing a stick in the woods here and trying to figure it out

 

[--weezl--]

no... header bolts have nothing to do with a vacuum leak, and your compression has nothing to do with the ability to bump start it... holding it's self while on a hill has a little to do with compression, but i wouldn't bank on that...

compression tests are easy to do, go to harbour freight, buy a compression tester, i recommend getting one with a threaded end, instead of a tapered rubber end, pull the wire off the coil, and ground it out, then remove one spark plug, screw the compression tester into the hole that the spark plug was in, crank it over, you want the motor to do about 4 full revolutions, so 2 seconds of cranking should do it... go look at the gauge, write down the number it shows, put spark plug back in, proceed to do this on the remaining 7 cylinders, your numbers should be in the 120psi ball park IIRC, and shouldn't be way off from eachother... if you have one at 110, and another at 120, no biggie, but if you're getting 120 from most, then one at 80, or 40, you've got a problem...

go do this, post the results in this thread, we will help you from there... i still suspect a burnt valve, but there could be lots of other problems... i assume this is still fuel injected right? they could have taken that off while doing the swap, and gone with a carb, but i suspect it still has the EFI on it, if it does, go also buy a Ford EEV-iv tester, and read the directions, if you can't find it, you can use an analog multimeter, but it MUST be analog, with a needle... you can also use a test light if you have one... this is how you do it... you will get a series of flashes or sweeps on the meter, a pause, another series, and a longer pause, these two first sets of flashes or sweeps are your first code... so if you get flash flash flash flash pause flash flash pause pause, that is code 42, it will keep doing this until all of the codes have been read, it will then repeat a second time. i forget where exactly in this sequence it is, but there is also a seperator flash, which is a long flash after a very long pause, it is just to let you know that it is giving you another set of codes...

your best bet is buy a code reader, it makes everything much easier!!!!

compression tester, code reader, use both, report back!

 

[adsm08]

You say the battery is low? Low system voltage can cause all sorts of running issues. A low battery should not cause crappy spark, but a bad alternator and a dead battery can certainly cause you all sorts of issues.

Charge your battery (something that needs to be done for a compression test) and then keep going with what Weelz is telling you. I think he is on the right track.

 

[--weezl--]

thank you sir!

actually, i meant to include the charged battery too... a dead battery won't get you too far...

 

[Iceman21]

I can't believe I over looked this, but it seems I launched the alternater belt... So I had no charge... Coupled with the loss of the header gasket, I think I figured out the issue!

 

[--weezl--]

i don't think you did at all... neither of those cause a serious lack of power, but if you think you got it then ok...

 

[Iceman21]

It actually did fix it. I replaced the belt and charged the battery and she's running perfectly fine now, starter wasn't even out, just the battery was that dead. Thanks for all the help you guys. I do have another question tho, what headers can I buy for this truck that fit the engine and go around the frame and what not

 

[--weezl--]

pretty much, shorty headers, most likely need a body lift, or something custom, other than that, not going to happen from what I know