- This topic has 29 replies, 7 voices, and was last updated 11 years, 8 months ago by
.
-
Topic
-
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!’ 😛
-
Replies
-
That truck is definitely worth rebuilding the 4.9 straight six is a great engine. Even better if it has a throttle body and a manual trans.
If I had the extra cash and only paid 1200 for the truck I would rebuild it If I knew I was going to actually use it for towing and hauling loads a lot.
You did hook up a vacuum gauge, I assume?
Negative on the extra cash. I haven’t looked into how much to rebuild, but i’m assuming its multiple thousands. Don’t have it.
I didnt hook up a vacuum gauge, but what are suggesting i check? The pcv is in good shape ( moves around fine when shaken) and the hose to the intake almost pulled the glove off my hand when I removed it. I didn’t check the smaller hose that supplies vacuum to the pcv, but its about 18 in long and sits on top of everything so I just assumed i would have noticed a problem with it. Now that i think of it, that vacuum line goes into the top of the air cleaner in the center of the circular air filter. There is a small device/valve/??? that it plugs into. Could that go bad? I’ll get a picture or something to show what i mean.
I would do a compressiion test and a leak down test on the eng. this way you will have a better idea of the internal condition and whether or not it will hold up to a long drive towing.
I found a compression tester for $20 on harbor freight’s website. Ill pick one up on my way home and post an update this evening.
If the PCV valve is not hooked to manifold vacuum.
it will not suck. If the PCV goes from the valve cover
to the air cleaner. It will push the air to the air cleaner.
hence the name Positive crank case ventilation.(PCV) Its normal
what is happening.blow pass will be more noticeable when you remove the dipstick when running you will get lots of chuffing and oil throwing up when the piston rings are nackard which compression will blow past the rings into the engine block and then force oil up through the dipstick hole ? thats my assumption anyway but hey assumption can be the mother of all f..k ups 🙂
just a quick note if the pcv is blocked it will force the oil anyway so make sure its not blocked first then if it still chucks oil up then its rings ?
And the results are in:
1: 150 psi
2: 90 psi (maybe 95 with some oil in cylinder to help seal rings)
3: 115 psi (maybe 120 with oil)
4: 150 psi
5: 150 psi
6: 150 psiThe pcv does connect to manifold not the air cleaner (my mistake). It works well as far as I can tell. Changed the oil recently and it was old and black, but no signs of coolant. Coolant is clear. Nothing comes out of the dipstick tube.
I’ve made a video of the truck running and the gases coming out of the breather and will post it when I get the chance to upload it. Aside from the sound and looking at the belts, its hard to tell its running because its so smooth, but maybe you guys would disagree.
I’d like to do a leak down to find the leaks, but i don’t have an air compressor. I was thinking about using a spare tire as an air resevoir since I have the hoses and what not to connect that, but I’m guessing I going to need more than 30/40 psi I’d guess.
Ideas? Thoughts?
Thanks in advance.
Here’s my idea. I’m not really experienced with this stuff, but I’m a learn as I go kinda guy.
It seems to me like the head gasket between the two cylinders is the likely cause. Could also be valves leaking. In either case, the head must be removed. So could I just remove the head, change the gasket and visually inspect the valves? Could I miss something with a visual inspection? Could it be caused by something else that this would not help if i did it?
Thanks again.
Motor running and I show gases coming out of the breather. Thats what prompted this thread. I cant get the hoses off the pcv at the end, but trust me that theres a good vac there. Engine rpm changes when hoses are removed due to the leak.
A friend is lending me there compressor. Ill perform the leak down tomorrow, then remov the head. I expect a head gasket leak btwn 2 and 3 and oil passage. Photos will be taken and posted.
Your video says private.I think the leak down test
is the way to go. sometimes its hard to tell if a
valve is sealing properly. by looking at it.keep us posted.First on the cylinders with the lower compression, shoot a few drops of oil into the cylinders and retry the compression test. if those cylinders come up, you at least have worn rings on those cylinders.
Second, if you don’t have and air compressor you may see if one of the parts stores have leak down testers available, if they do, then network to see if you can find someone who will let you use their compressor at there place, a leakdown tester is the best way to determine if you have blow by and where it is coming from.
Third take the oil cap off and place a piece of cardboard over it with the engine running, and the pcv installed and see if the engine will have enough vacumm to hold the small piece of cardboard to the valvecover.
The last suggestion should be tried first.
- You must be logged in to reply to this topic.