Engine smoking

[hemicharger69]

There's a good amount of exhaust coming out of the breather cap. I think engine needs to be rebuilt. Power is sluggish.

Can I just rebuild the engine without pulling the block out?

I do not have a lift or cherry picker. I just want to send the heads out and replace piston, rings, cam, rods, etc all the moving parts myself without decking, boring, honing, etc. Maybe master rebuild kit?

Budget and limited work space are constraints.

Anyone done this?

[michaelperazzo]

I would do compression tests and see if all the cylinders are ok, get an idea of the health of the engine and head gaskets. If it is a high mileage motor, it will need a rebuild and doing it in the car is not the way to go. Maybe give that "Engine Restore" stuff a shot.

[RedBird64]

Agree with compression test. Another rather odd test is to drive it at night in traffic and when you stop, look in your rear view mirror for blue smoke. The car in back of you will light it up (I don't know if more modern headlights will do it though). You can't see it in day light (unless it's REALLY bad).
If it has good compression, no smoke, runs good and doesn't use much oil per tank of fuel, you may be just fine. Some blow-bye is normal even with a new tight engine.
390's were always oil burners. Yo can switchto a heavier oil like 15 or 20W-50 to slow down oil consumption (what I run).

Scott

[ICON 1956]

How many miles on the motor? is there any smoke coming from the motor other than the breathing cap. I would do a compression on the motor first, Always do the simple things first never just assume the worst and tear out everything. check timing, spark plugs, any adjustments on the carb, gas mixture. I would do all the simple things first and then to the next step. Also go the the web site for 390 FE forum for ford engines, these guys really know their stuff.https://www.fordmuscleforums.com/forumindex.php

[hemicharger69]

I finally did a compression test this weekend.

Cyl:
1 - 180
2 - 160
3 - 160
4 - 185
5 - 185
6 - 170
7 - 160
8 - 170

The engine knocks on start up. Dwell is 25-31 degrees. Timing is correct doesn't seem to have unusual adverse affect when adjusting. I had to detach the vacuum advance hose. Otherwise, the engine stalls when I give it gas. Throttle choke is opening as it should. Idle screws backed out 1 turn from engine rpm dip.

Do you think it's an engine timing issue? Or an ignition issue?

[Karl]

What fuel are you using?
The vacuum hose should be attached. Other factors must be causing the engine to cut out.

[bbogue]

I may be able to shed some light on the vacuum advance issue. Assuming it was attached to the ported connection on the carburetor, at idle there is no vacuum so no timing change. But when you open the throttle, manifold vacuum comes in, operates the vac advance and increases timing. BUT, if the bladder of the vacuum advance is leaking, you would be getting a very lean condition which might explain the poor running. A simple test...suck on the line from the vac advance. If it won’t hold vacuum it’s time for a new one. Good luck.

Bill

[RedBird64]

Your compression numbers are too varied and a little low. If (big if!) it's the orig eng, I would expect to see 180~195 PSI. No matter what eng it has, they should all be well within 10% of each other which they are not.
Sadly, no timing adjustment or state of tune is going to cause it to have blow-bye. It sounds like it needs a total rebuild and that requires the eng be removed in its entirety.
BTW, without vac. adv. the throttle response will be very sluggish and power will be down but it will run smoothly.

Sorry for the bad news.
Scott

[bbogue]

A few thoughts.
I agree that the variance in compressions between cylinders is troubling but I think some would say the compression is decent for a 130K mile engine if everything else is ok. My engine’s compression was around 120-140 psi before its rebuild. It also had a knock. Compression after a rebuild varies with what’s done and the parts used. In my case it’s now about 160psi. I think some would say yours might be usable a few more years if you can determine the blow-by is something other than piston oil rings and address the knock. A couple more checks might help you make a better decision. A leakdown test would help further determine the condition of valves and piston rings. More than 10% leakage is unacceptable. Listening during the test at the exhaust, carburetor and oil fill tube will help you determine where the leakage is coming from. I would also pull the valve covers and check the condition of the valve seals and whether or not the drain holes in the head are blocked with sludge. Either of these issues could cause oil to leak past the valve guides into the cylinders. The tapping at startup could be just a bad lifter. If the sound is deep in the engine that’s more likely a bearing.
The folks on the FE Engine Forum (now on Tapatalk) have been very helpful to me over the years. Some expert engine builders. You might post over there. Let them know your limitations wrt budget and ability. You may find an expert near you to help.
Having said all this, I’d be reluctant to do anything other than a full rebuild (pull engine) if it hasn’t been touched in 130K miles. It’s time.

Just my thoughts. The experience of others is likely different. Best of luck.

Bill

[Aaron65]

I drove my '65 Mustang 289 probably 20+ years and 75,000 miles (for a total of 135,000 on the lower end) with the compression ranging from 115 to 150. It had the original lower end and a set of junkyard heads on it I installed when I was 17 and paid $100 for. A sunken exhaust seat finally took it out about 7 years ago...it just quit firing on cylinder #8. Stop and breathe before you start committing to a full rebuild.

First, your lowest cylinders are about 14% lower than the highest. There's no way I would pull an engine because of that alone. Heck, the old Motor and Chilton manuals recommended that there could be over 20% variance before doing anything about it. Obviously, that's not a perfect engine, but if you drive 1000 miles a year, like many do with their collector cars, you could get 10 years or more out of that thing.

I'm not trying to disrespect the advice of others here, but it's easy to spend internet money. I'd be doing a ton of diagnosis before even thinking about dropping what it will cost to rebuild an engine.

Regarding the cutting out when the vacuum advance is pulled: check the wiring inside the distributor too, in addition to the diaphragm as mentioned above. As the diaphragm pulls on the advance plate, you can get excessive dwell variation from a worn points plate, or you could even ground the points wire if there's a bare spot. You may just need a new distributor or a rebuild in that regard.

Have you made sure your PCV system is working correctly (considering the breather smoke)?

[RedBird64]

The problem with continuing to drive a worn eng (esp one that's knocking) is some parts that you would normally keep, like the crankshaft, may get beaten to death.

BTW, My advice was just that, my advice and what I would do (with my own real money) after 40+ years of driving and working on FE's.

Good luck,
Scott

[Aaron65]

It was absolutely not my intention to single you out with my comments, Scott. Your concerns are, of course, totally valid.

The original poster mentioned that the engine knocks on start up. I'd want to determine what is knocking...a lifter? A rod? Does oil pressure take time to build at start up? It could have a clogged pickup, a bad oil filter, or totally worn rod bearings. I've not had my T-Bird long enough to even think about pulling the pan in-car...is there even room?

[El Leon]

Nobody has mentioned doing a leakdown test? Add a little bit of oil in there and you can quickly identify a leak well beyond what a compression test will reveal.

Overall though, that's got to be a tired motor by now. If you know for certain what condition the block is in and how many times it's been re-bored, then you might just build a new motor and swap them over so you don't have downtime.

[RedBird64]

Nobody has mentioned doing a leakdown test? Add a little bit of oil in there and you can quickly identify a leak well beyond what a compression test will reveal.

Overall though, that's got to be a tired motor by now. If you know for certain what condition the block is in and how many times it's been re-bored, then you might just build a new motor and swap them over so you don't have downtime.

Yes, a leakdown test was suggested.