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So I bought a truck off of craigslist…
Not surprising that there’s a problem. Its a 1985 Ford F150 with a 4.9L inline 6. The odometer says 3000 mi, but only goes up to 99,999, so its rolled over once or twice perhaps. The previous owner (for 10 yrs he says) was an elderly man who had a volvo he drove everyday, so this truck didn’t see much work for the last 1/3 of its life.
Most of the electrical components are new (starter, voltage regulator battery, plugs and wires), new clutch. It had an issue stalling (had to have it towed twice), but turned out to be a fuel pump issue, now replaced.
It runs great as far as I can tell. I hauled 5 loads of wood (from an old tree that recently fell) from half an hour away without a problem. It lost a little steam on steep hills with a full bed of wood, but otherwise ok.
My concern, the breather from the air cleaner doesn’t suck in air like it should, air comes out. I checked the pcv and hoses. Theres a good vacuum from the intake and everything. I’ve been told/read that this is likely blow-by due to worn piston rings. I’m not going to rebuild an 85 that I paid $1100 for.
However, the reason I bought it was to tow a 15 ft bass boat that my boss is going to sell me.
Is it a bad idea to tow with this truck? Will it likely leave me stranded one day? I’d like to tow the boat up to 9 hrs away for a vacation this summer. Bad idea? Or is this the sort of thing that will just cause bad mileage and wear down slowly (ie. I’ll know when its time to retire it before it dies with the boat hrs from home)? The boat supposedly only weighs 1000 lbs (fiberglass).
What do you guys think? I mean aside from ‘You shouldn’t have bough a 28 y/o truck from craigslist!’ 😛
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Thanks for the input. The oil did not help compression values (noted above). The oil cap and the breather go the same place, so if positive pressure builds there and blows out gases, it will at the oil cap too.
not sure why the video isn’t working, but it shows the breather problem. i’ll put a link below.
I show in the leak down videos that the cylinders leak into the valve cover meaning into an oil passage in the head gasket or through piston rings. The rings would have to be pretty bad i’d guess to not improve with oil added (I used 3 squirts from an oil can). Valves seem to be ok because nothing can be heard at the exhaust or intake, however in the vid for cylinder 3 you can see the leak is so bad that a small leak from the valve could be possible.
Also oil on the plugs (see pic) apparently is a sign of head gasket leaking.
From 1985 f series shop manual ( found a copy on ebay ): If two adjacent cylinders indicate low compression pressure and squirting oil on the pistons does not increase the compress, the cause may be a cylinder head gasket leak between the cylinders. Engine oil and/or coolant in the cylinders could result from this problem,
[IMG]http://i790.photobucket.com/albums/yy184/EvoGeo/563.jpg[/IMG]
So, am I missing something? Anyone think it could be something other than the head gasket at this point?
Thanks for your help. I’m gonna look up some beavis and butthead on netflix now…
I believe it’s your piston rings, because whistling or hissing out of the PCV valve, oil filler cap hole, or dipstick tube means the air is pushing past the rings.
Also, did you check your coolant for bubbles? Air bubbles in engine coolant seen at the radiator filler cap could mean air escaping into the coolant past the head gasket.
I’m sure Eric will steer you in the right direction when he replies.
Anyway, you have a very clean and nice truck.
nice truck. During your leak down, did you have both plugs out of the head? If you did and a head gasket was blown as you suspect, you would have a large amount of air passing out of the ajoining cylinder that did not have the air attached to it. also in most cases of this type, a blown head gasket is usually involves the cooling system. it would be extremely unusual for a head gasket to blow on this engine and no effect the cooling system. Iassume that the oil is clear and not milkey. whilee the air is attached if you had taken the radiator off it would confirm the integrity of the cooling system. this is just another piece of evidence to help determine where the real problem is.
There were no bubbles in the coolant.
Also I did have both plugs out and did not notice air coming out of the opposite cylinder when I did the test yesterday. Just tested again and the majority of the air just comes out of the breather hole. I plugged it with a nitrile glove and could still hear a leak, but I could smell a little gas when I pressurized 3. Also a piece of tissue held across the opposite hole fluttered just a little bit only when air was applied (I checked it back and forth with and without compressed air to be sure it wasn’t the wind or my hand because it was so slight).
The gas smell would mean intake valve, right? I don’t think that explains the pressurized crankcase/valve cover though, unless I have bad valve stem seals. Even then, the majority should be leaking out of the carb and a little into the valve cover.
I am now leaning toward rings. With 3 at TDC compression, 2 is 60 degress behind so it has 15 degrees left on its intake stroke. The air goes past 3’s rings, past 2’s rings, then out both the intake and spark plug hole.
If im right then I should get exhaust valve leak from 3 when 2 is at tdc compression because 60 degrees ahead is 15 degrees into exhaust stroke. I’ll double check that as soon as this compressor’s over heat safety cools.
My question now is can I tow with this with worn rings? As you can see from the video, it doesn’t seem to run bad at all. With a bad head gasket I was afraid that it would deteriorate and leave me stranded, but is there the same concern here? I can do a head gasket, but piston rings… the manual says to lift the motor off its mounts with a jack and prop it up with wood blocks so you can remove the oil pan and then pop the piston out of the top of the block. Thats a head gasket times 2!
Alternatively, would you feel bad selling this to a friend with worn rings if he were just going to drive it around town (I’d tell him obviously)?
Ok I tested cylinder 2 and was able to hear air at the tail pipe with the plug in 3 and not without. So I have some air moving between the two cylinders. I can’t get much pressure into either without the engine rotating and the glove popping out of the breather hole. The tank only had 80 psi in it and the engine rotated before i could get the valve half way open. All the tests before were with valve on the compressor just cracked open, since its a 2 gal I was trying to leave some time to look around before it emptied.
I was gonna take the head off today to get into replacing the head gasket, but I’m going to wait for some more feedback from you guys.
From what you wrote, I don’t belive you had the cylinders at exactly tdc. if the cylinder you where putting air into was at exact tdc, you should not be having an issue with the cylinder turning. if you have the cylinder off a few degrees it will rotate when air is added to it. also need to make sure you are on the right stroke for the sylinder being tested. Eric had a video on how to reach tdc that works a hundred percent of the time for finding tdc. I saw it on you tube. I have used this technique for several years, however he explains it as well as anyone I kknow.I use this technique when I change valve stem seals with the head on the engine, believe me that is not the time to have the engine to rotate.
Good Luck and Keep us posted on your progress.Poof!
[IMG]http://i790.photobucket.com/albums/yy184/EvoGeo/truck319009.jpg[/IMG]
Manifold is now off. Not that bad of a job so far. All hand tools and penetrating oil. No prob.
So I’m posting this because I’ve found some things that make me more confident in my initial ‘diagnosis’ of a head gasket leak.
Exhibit 1:
[IMG]http://i790.photobucket.com/albums/yy184/EvoGeo/truck319006.jpg[/IMG]
Not sure if you can see it but there is a brown oily sludge in the radiator hose. It moves like oil, not water (I’m looking straight down at the hose and its still there), and its not gritty (ie not rust).
Exhibit 2:
[IMG]http://i790.photobucket.com/albums/yy184/EvoGeo/truck319010.jpg[/IMG]
Is that coolant leaking out between the head and block? Its a little exaggerated because the penetrating oil flowed down on either side of what I’m calling a leak, but if you look close you can tell what it would look like without the oil stain. Looks like crusty coolant all the way down the block to me. BTW that’s cylinder 3 exhaust at the leak.
Also I think I’m catching an oil leak from the valve cover at the same time (very top left in the last photo).
I’ll get to the head on friday most likely. I’ll post more pics then.
If the guy that sold this to me thought he was getting out of a problem vehicle, I’m getting more confident he goofed. After this I’ll be into it for $1600 (that includes 1100 to him, tax, tag, title, new oil, plugs, filters, and a fuel pump). And working on this truck is a breeze. I did valve cover gaskets and spark plug wells on my subaru impreza and it took like 10 hrs with a valve adjustment. I’m at 2 hrs now with this.
I did take the head off friday. I thought I had posted, but I guess I didn’t. My bad.
Here’s the shakedown:
[IMG]http://i790.photobucket.com/albums/yy184/EvoGeo/016.jpg[/IMG]
[IMG]http://i790.photobucket.com/albums/yy184/EvoGeo/017.jpg[/IMG]
[IMG]http://i790.photobucket.com/albums/yy184/EvoGeo/018.jpg[/IMG]
[IMG]http://i790.photobucket.com/albums/yy184/EvoGeo/026.jpg[/IMG]
[IMG]http://i790.photobucket.com/albums/yy184/EvoGeo/029.jpg[/IMG]
Valves all look good, guides good, push rods good, fulcrums good. Tappets are slightly worn, but I think I can live with it. They are suppose to be ever so slightly convex on the foot, and they are ever so slightly concave. If i replace them I’m supposed to replace the cam shaft too, so that will wait. I can do that without getting this far into the engine (valve cover, pushrod cover, and timing cover, bam).
I am having trouble cleaning the head mating surface. It seems like the metal has absorbed the gunk! Any suggestions would be greatly appreciated. The guy at auto zone suggested shaving cream, and I’m done playing with it. Also, what’s good to clean the valve components?
The valve components being steel can soaked in lacquer
thinner or they sell parts cleaner at the auto part store.
its either 1 or 5gal. use a small wire brush to scrub.
They also sell liquid gasket remover.
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