So I blew the gasket in my '94 4x4 F150 sunday.


Was mad at it, and drove the ***** out of it, and blew the gasket. yay

Still runs and drives fine though, and only realized it when I got home that that was the problem. Drove home 35 miles.


I think this is related to a few months ago, on the coldest day of the year (-15*F), my water pump failed 6 miles from home, and it severely overheated (taught temp gauge was playing games with me since it was sooo cold), and guess it cooled down to quick, and warped the head.....and my really hard driving sunday, done it in.


Temp gauge goes up hot, comes down, goes up, down, up, down once it's fully warmed up. Opened hood sunday night cause I smelled burnt oil, and I saw the dipstick had blew out half way, and it made a mess, and the oil is getting lighter in color, and theres coffee on the oil fill cap.....and when you take the oil fill cap off with engine running, it looks like an old steam locomotive! Found that out today, and now it's puffing out smoke rings from the exhaust. (haven't driven it since sunday night, just fired it up today to confirm that was it).




So how bad is it, doing a head gasket on this straight 6... in the truck? I'm not real worried about getting the head off etc, it's all the EFI stuff that concerns me.....?




Oh, and off subject, anyone ever hear of a fan clutch spinning it self off?


Again sunday night, shutting down the engine meeting friends, I hear a big CLANG when I shut 'er down, the hell was that? Look under, my fan is sitting on the ground!?!? No damage to anything, didn't even touch the rad, just spun right off and fell on the ground????? Tread looks fine and everything. Still scratching my head on that one.

 

You might have a warped head now not a hard job to pull the head .when you get the head off check it for warpage also check the valves make sure none have seized up broke or bent. If head is warped over .007 should have engine machine shop check lt out or just find a good used one

 

I doubled Head gasked one one time for a cheap fix for a guy told him it make lack power it did .A month later Iput on a good used head. i have did at least 3 of these all from a overheat issue broken fan belt or blown radiator hose

 

Yes, a head gasket/head is a fairly big job.

The worst part of the job will probably be getting the intake/exhaust on and off. The rear exhaust manifold is a bit of a pain because of the egr tube.

The manifolds seem to have a tendency to crack. I still have my engine out and I can see the start of a crack on #6. My spare one from the parts engine also looks like its getting ready to crack in the same spot but I think it will be ok. My lower intake also had an ear cracked off, looks to have been cracked clear through for years but seemed to still be sealing. Spare intake looks good.

My point being there is a fair chance you will find more issues than the gasket/head when you take it apart.

The wiring/hoses associated with the efi/computer control aren't too bad at all really. Take a couple photos or mark some with a paint pen and you should have no trouble.

Its impossible to say without taking the engine apart and looking/testing what the damage is, but the straight 6 head is pretty long and prone to warpage even when it hasn't been overheated. I for sure wouldn't just assume the head was ok. I would also check the block for cracks at least as good as you can by eye.

At this point I would have to consider whether or not to just get a good used engine and drop it in, or at least start to consider it.

I would have to look at the general shape of the engine. Does it have good oil pressure? Oil leaks? How about compression? I would definitely do a compression test first before pulling it apart. With the dipstick being blown out I would have some ring concerns. Same with the blowby/vapor from the oil filler cap and the rings out the tailpipe. If its all water vapor you might be ok, but if its smoke you either have a badly cracked head or bad rings/cracked block.

It kind of boils down to what you want the end result to be and how much you can afford to spend versus the extent of the damage and/or other issues.

National Cylinder head will rebuild a 4.9 head, and they do really good work - at least the one here does - for $195 plus any parts it might need, welding is extra if it needs it. More than a used head, but you know its good. Changing a head/headgasket on anything is a lot of work, would really suck to have to do it again.

They also have good prices on gasket sets, but even felpro isn't too expensive for a head set, around $50 I think. Headbolts are prob about $20.

I'd figure at least another hundred (if you're lucky) for suprises. So you can figure at least $370 for a quick in and out head replacement if everything else is good. Plus the cost of oil/antifreeze which you would need whether you change the head or drop in a different engine.

Prob a good time to replace the freeze plugs too, only about 15 bucks for a set of brass ones at napa and they will be fairly easy to reach with everything apart.

its always a bit of a gamble to replace just the head/gasket on any engine but the 4.9 is pretty tough so if you have good oil pressure and compression it will probably live. If you don't have good compression or oil pressure, or find any cracks then I would say you would definitely want to find another engine or plan on spending a lot of money.

Copper coat is a very good product by the way, I strongly suggest using it.

 

Yeah it's a big job but that don't mean much... just that it'll take a while. It is what it is, so just break out the tools, grab a cold beer, crank up the tunes, and tear into it.

I used to look at things and fret over the easiest way to get to a certain component. Then I wisend up and quit caring... now I just tear stuff apart without a second thought until the part I want to repair/replace is on my workbench. Saves me the frustration of trying to work around other components.

If that was my truck, I'd check compression and make sure the base mechanicals were still good. If so, then I'd rent/borrow a shop crane and pluck the engine right out of that thing. Set it on the ground in a comfy work area, tear it down to just the short block and while the head is off to be machined, I'd replace everything that could or currently is dripping oil... the pan gasket, both main seals, oil filter adapter, etc. If oil pressure was ever questionable, I'd do an oil pump too.

If later on you discover that this engine ain't worth fixin then half your work is already done for you since it's already out of the truck.

Then when your engine is back together or you've decided to replace it with another, just bolt it back in, reconnect everything, oil/coolant, and you're done!

 

One unexpected thing to be prepared for is a broken head bolt or two. I found I had two that were broken which made me thankful that I had already decided to just replace the whole engine.

If I was going to replace the head - and I did consider doing just that - I would encourage you to investigate getting one of the new ones that is supposed to be "better" in some ways. It was not much more than a rebuilt one (maybe $50 more) so it was a no-brainer in my mind. There should be some links in a thread I had going from about May of last year.

 

The truck has 98k miles on it.... and oil was always pretty clean after a 3k oil change, so looks like it's been maintained. Truck has no trailer lights, never had a hitch, or even bumper ball so it's never towed anything either.


No oil leaks, pretty clean engine actually. Exhaust manifold must have a small crack, cause when you put a light-heavy load on it, you hear a ticka ticka ticka ticka coming from the engine bay.


I wanna avoid pulling the engine, cause that involves separating the tranny....



Anyways, i'm still deciding. If I fix it, it'll be just to finish winter with it, then I have my van for summer anyways, and I'd get rid of it. I never liked it enough to justify keep spending money, and doing this kind of work to it. It's a fun little truck yes, being 4x4 5spd and short wheel base, but it's a '94 and I hate that interior with all my heart. It's EFI to top that off....


I have an '86 F250 Diesel to go see this weekend, depending what happens with that, will determine what I do to this one I guess.

I'll keep you updated, and if I do get the wrench out, i'll start on a write up thread on it.


I did the head gaskets in my Diesel van last summer, and everything went very well, so hopefully I get that luck with this thing to.

 

Pulling the head to replace a head gasket on an I-6 should be a walk in the park compared to replacing head gaskets a diesel in a van!!