I'm pretty sure my new-to-me 1991 F-150 needs a headgasket.

The clues:
White foam on the oil filler cap
More oil now than when I filled it up after the last change
Milky looking oil when I drained it
Missing several quarts of coolant

So what am I in for? I've never attempted a major engine repair like this before.

What problems am I likely to run into?

What other gaskets or parts should I replace while I'm taking it apart? Intake/exhaust gasket? Throttle body gasket? Should I have the intake manifold and throttle body cleaned while I have it off?

What tools (besides a torque wrench) am I going to need?

Lastly, and probably most importantly, how do I know it's a head gasket and not a cracked block or cracked head? Is there any way to check either when I have it apart or before I dive in?

Thanks guys... *sigh* I wish I'd have looked at the filler cap before I bought it.

 

You can get what is called a head gasket set from Felpro which includes all the necessary gaskets for the job. I think they even give you valve seals which you might as well replace while the head is off.

Once the head is off you can sometimes see on the gasket where the leak occured. I don't think it would be a bad idea to take the head to a reputable machine shop and have them check it out. They will check for worn valve guides and install the seals. You can get them to lap the valves or give them a grind. No sense in grinding them if they don't need it. They can magnaflux the head and check for cracks.An honest machine shop will let you know what you need to do. I think they run them across a milling stone as well to ensure flatness.

Don't let them know you are a beginer or they may take you for a ride. Hopefully you know someone you can trust. Hard to find these days. Dont forget to inspect the cylinder walls and water passages for cracks. The new head gaskets usually require no sealer or retourqe. The gasket should be blue if it is Felpro Permatorque. By the books they say you have to use a thread chaser to clean all the head bolt holes. True enough debris in the threads can effect proper tourque so use your own judgement. A lot of folks dont do anything to the threads. You do need to dip them in motor oil and use sealant on any bolts that pass into water jackets.

By a good 180-195 degree thermostat. Factory is 195 degree.

Use plenty of PB Blaster several times on ALL the exaust bolts before you start the job.

I'm surprised no one else could offer any tips for you. I hope these will help you. Maybe some of the other guys will jump on this one soon. Hope so...

 

I am getting back the head off my '86 today. Plenty of PB Blaster is good advise. Mine is a carbed engine - your's is a fuel injected; but, once you get the FI off it's basically the same to remove the head. The head weighs about 80# so it's a big lift over the fender. Get some tape to mark connections when you take them off - it may be a week or so until you are able to put it back together again and the tape markers will help you remember what goes where. If you are not sure - try to get a Haynes or Chiltons manual for instructions.

 

I've got an el-cheapo digital camera, and found that taking a few pics as I go often clears up reassembly when something's gotta sit for a few days. What you've got here so far is all good advice. Close inspection of the block and head surfaces and gasket will usually reveal where the gasket blew. Also, if yours is like my '94 ( I hope not) inspection of the head might reveal a crack before you take it to the shop. If you don't see any, take it and get it checked by pros, but you might not need to, if it's really obvious. I'd also recommend a die-grinder with a light roloc disk to clean up the deck of the block without damaging it. stuff rags in the bores to keep particles out. Also check your pushrods for straightness while it's apart. I had a couple that had very slight bends in them when mine was down, and you can get OEM ones individually pretty cheap. When I got ready to actually pull mine I stood in the eng compartment on the driver's side and lifted it up onto the radiator support, then climbed out and moved it to the bench. There's a lot to take apart on an EFI to get the head, so tags, notes and pictures are all good ideas.

 

I don't like the amount of coolant you are finding in the oil!! I think the majority of 300 gasket leaks cause coolant to burn off or leak out, I would take your time and get as much info about the engine as you can before taking it apart, Have you checked compression of the cylinders.? What is the color of your exhaust smoke? Is the engine running hot or cold, is it idling and accelerating ok?? Yes everything points to a gasket, but you have a severe leak for a gasket.

When I did my whole engine last year, I had the air intake plenum hot tanked, it had alot of black deposits in there. New TB gasket, valve cover gasket, lifter cover gasket for sure, Clean the exhaust DP and EGR feeder tube. I bought a tap to clean the threaded holes at the exhaust and intake, the threads were garbage after 12 years and cleaning them made the manifolds bolt on the head much easier than they came off,Be very careful of the vacuum lines!!!! Removing the plenum and head is tough on the lines cause they are wrapped right around the head. It is a great time to replace the orings on the injectors, although they should last 20 years. Is the water pump original? good time to change it. New Tstat for sure.

 

Coolant is going elsewhere for sure. The paperwork I got with the truck states that the water pump was replaced in 11/2004 at 144,944 miles. One would assume that the shop did the correct thing and filled er up when they were done. Well, yesterday I looked in the radiator and it was almost empty! I put about 6 or 7 quarts into it to fill it up. Today the truck has 146,245 miles on it. I haven't looked closely at the exhaust. I will do that tomorrow. It isn't leaking, however. The truck has a new radiator, heater core, and new hoses. No visible leaks.

I have not done a compression test. I had enough to do this weekend! That will be next, though.

What's the difference between a lifter cover gasket and a valve cover gasket?

I'm worried that I'm going to screw this up and destroy the motor. This is far more complicated than anything I've ever tried before. Should I just buck up and pay a shop to do it? I have a good mechanic that I trust. I'm worried that I'll get halfway into it, get in over my head, and end up having it towed someplace after I've caused more damage than there was to begin with.

The truck runs like a champ, though. There's one EVP code, but that's it. Starts, idles, and drives absolutely perfect. Temp of the coolant in the overflow tank is 205, so it's not overheating.

 

Andy, I dont think you are going to destroy anything removing the cylinder head and trying to find out what is going on. 924x2150 had some good advice as far as trying to get an idea what is wrong without taking anything apart. The way I see it though is no matter the determination based on symptoms the head will be coming off any way you look at it. I think the worst damage you could really do would be to wring off a bolt or strip some threads somewhere. I guess you could botch the job somehow and have to do it over but nothing will be unrepairable. Two things to remember in a head job.

1-compete cleanliness of mating surfaces
2-proper tourque in proper sequence

I think it would be more ideal to do your first head job on a '71 as opposed to a '91. Much simpler as far as disconnecting everything. I think someone else mentioned labeling every vacuum hose or whatnot. Draw/take pictures, make diagrams. One last thing make sure every part you remove from inside the engine, namely rocker arms and pushrods gets labeled as to its position or place. Replace all engine parts in exactly the same position as they were removed. As far as towing goes call your insurance company and have them put towing insurance on you policy. Really, I think mine is like $3 every 6 months. That way if you have to turn it over to someone else, or later you have other trouble on the road you are covered. You could even drop it after you finish the job. Don't feel bad I'm sure any company you have ever paid an insurance premium has more than happily lined their greedy pockets with your likely hard earned dollar.

 

Hey Gregtruck I don't understand this insurance idea, I thought that towing ins. covered your tow from a car accident scene to the repair yard. Maybe AAA road service would work better, but a tow should only cost you 45 bucks, and the AAA might be thirty a year.
The lifter cover ....nix that...I mean the pushrod cover is on the distributor side of a 300 I6 and basically behind the dist. it is just another oil leak spot for old I6's

You are right to be concerned, it is a difficult job to do correctly. I have seen many cars abandoned in the driveway in many pieces never to be reassembled.You need to ask youself " What will I use to get around to work or whatever, in case the repair takes me 3 months for lack of money, tools, initiative, or just to darn busy elsewhere? If this isn't a 7 day project, will the truck be a bother to someone as it sits on jackstands for 3 months? Where will you keep the parts safely stored while they are waiting for re-assy? Do you have enuf tools? The answer is no!! I always try and do repairs myself, because I like the quality of my work, I spend money on tools I need cause I'm saving on labor also, and evry time I repair another system I gain confidence, knowledge, and the satisfaction of self-sufficiency. One good thing that has happened is the availability of free rental tools. I don't think we had that before the 90's, we always had to actually pay to rent tools or had to outright buy tools we were only likely to use once. Now every auto parts store wants you to use there tools for free as long as you are coming thru the door and are likely to buy some parts, oil, or accessories.

If you are the type of person that finishes everything you start, then go for it, if not take it to a shop. You need to be able to analyze the situation, make the best moves based upon info you find on the internet and thru repair manual procedures that leave you hanging.

 

At my company you can just pay a little extra for coverage of towing expenses. Its not a AAA type thing where they come out and cater to your every need. Simply if you need a tow for whatever reason you turn the bill in to your agent and they reimburse you for your expense. There is a mileage limit. Thats about it. They dont ask why, when, or where.

I can't believe there are people who feel the need to have or pay for Onstar and GPS. I mean sure it would be OK to get on the cell phone (that I have never owned) and have a 21 year old girl 1000 miles away unlock my door because I lost my FREAKING remote with the doors locked. Come on people! How much common, basic, responsibility can we possibly shed in the "dumbing down" of America. Nobody will ever get me to put my $$ into a vehicle that is full of unnecessary gadgets that will break probably sooner than later. What was wrong with a KEY to get in your door and why do I need a remote to control a stereo that is right in front of me? I don't even like power windows. I guess these are a couple of reasons why I like vintage vehicles. None of the stupidity of modern times. No payments also......

 

Ok, I've talked to some people, done some research, thought about this, and here's what I'm thinking.

$1100 for headgasket including a head job. After wrestling with it, I'm just not 100% comfortable doing it myself. That's the shop price.

$1400 + core + misc. stuff for a reman motor. I'd do the install myself, as I feel a lot better about doing a motor swap. It just seems harder to screw up, as long as I'm careful.

So why wouldn't I spend another couple hundred and get a brand new motor out of the deal? Then I have a motor that I know the history on, and I know has never been overheated, had a Fram filter on, or had Pennzoil run through it. Plus, I really want to get 300k out of a motor, and I don't think this one's going to make it.

I've noticed a pretty good knock when I rev it to 2700 or so. It also rattles on startup, even with a good filter on it. I'm thinking this one is just tired.

So my questions:

Does all this make sense?

Does it seem silly to be more concerned about my abilities when doing a headgasket than a complete motor swap?

Am I underestimating what's involved in a motor swap or overestimating what's involved in a head gasket job?

 

Option #2... If you have a work space, such as a garage, and if your truck will run for a while longer, why not buy an engine stand, about $130 bucks, go to the junkyard and get a mystery motor and rebuild it yourself. The advantages are: you will learn exactly what it takes to disassemble and repair any component of the engine, you might save a little bit of money, that depends how lucky you are and if the junkyard sells the engine at a reasonable cost, you can be sure the engine is built with quality, and great attention to detail.
The problems: possibly having to count on a machine shop to correctly, mill the head and deck for a reasonable price, or other services you may need such as hot-tanking, pressing bearings, assembling the head for you, or polishing/porting. the price of parts could make it too expensive, engine rebuilders get discounts when they buy in bulk, we don't.

You mentioned some prices and said there would be some miscellaneous costs. small things like gaskets, thermostat, new coolant hoses all add up quickly. The rebuilt engine may have a warranty that stipulates new water pump required for warranty. I bought a Jasper long block 300 it cost me 1600 or 1800(I forget), and they sold me an installation kit for another 250 bucks, it had all new hoses, tstat, gaskets and water pump. It was a good deal. After I bought the engine, the install kit, and bought more stuff at my local shop that I thought I should change, I ended up spending close to 2500 bucks, and I had to do all the work.

Edit: Still thinking here....It is alot of work to change an engine, every part must come off. A long block comes with new oil pump and screen, an oil pan and gasket, head, pushrod cover, timing gear cover. You must install the following parts on the new block after you remove them from the old motor: valve cover and gasket, water pump and gasket, thermostat, thermostat housing and gasket, harmonic balancer(damper), fan pulley, fan clutch assy., right and left side accessory brackets, distributor, all vacuum lines, reconnect all wires, all sensors, solenoids, dipstick, motor mounts, tranny plates to crankshaft, align the new motor to tranny, exhaust and intake manifolds and gasket( those bolts are a pain in the butt) EGR valve, reattach EGR pipe, starter, on and on, etc. etc.

The third option!!!! Price a remanufactured ready to bolt-on head. You will have much less work than a block swap. I think I have heard a reman head is 400dollars or so.

There is one big question however, are the pistons, bore, crankshaft and bearings damaged from years of coolant in the bottom end?????? Coolant has an adverse affect on those things, the only thing that should be in your crankcase is pure old atmosphere and quaker state. When the crank components are exposed to combustion gases and coolant they start wearing out, and you can get the kind of rattling that you were mentioning .

Did any mechanics look at the truck and recommend a complete swap???

Good luck, I wish you were getting some more advice on this thread, maybe somebody else has some other ideas, but an engine that has suffered through many miles with a major leak is often in need of a complete rebuild.