1980 3.0L strange overheat issue

[Scott Danforth]

Bring the head in

 

[mickyryan]

did you check exhaust for broken flapper stuck in outdrive? i had a 3.0 had that problem they replaced entire engine still had same issue sold boat to me i started trying to figure out what was up and found half a old flap wedged down at the outdrive

 

[Troubled1]

did you check exhaust for broken flapper stuck in outdrive? i had a 3.0 had that problem they replaced entire engine still had same issue sold boat to me i started trying to figure out what was up and found half a old flap wedged down at the outdrive

Where are they located? Would it be where the exhaust adapter meets up with the outdrive?

 

[88 Capri (2022 SOTY)]

Where are they located? Would it be where the exhaust adapter meets up with the outdrive?

The flapper is in the upper section of the exhaust pipe, you would need to remove the upper elbow and rubber coupling. It's in a very similar location as my Ford 2.3.
All that was left on mine was the pin, the flapper had long since melted, I did find small pieces in the outdrive when I had removed it.

 

[Troubled1]

The flapper is in the upper section of the exhaust pipe, you would need to remove the upper elbow and rubber coupling. It's in a very similar location as my Ford 2.3.
All that was left on mine was the pin, the flapper had long since melted, I did find small pieces in the outdrive when I had removed it.

Ok. I have the riser and coupling hose off. I’ll look inside and see if it is there. I went through my manual a couple times and there was no mention of it. I looked for the part online and only found one listed for a Cobra not a stringer.
I’ll verify visually.

I check inside the exhaust outlet below the riser, this one does not have a flapper or any way of installing one. I wonder if stringers May have had something built into the intermediate housing?

 

[88 Capri (2022 SOTY)]

Oh you have a stringer, the image was from my manual which was for a cobra.
I've never had a stringer but it may be the same or similar. It should be accessible somewhat easily either way, it should be higher in the exhaust system above the water line.
I'm not sure if I have anything about stringer drives, if I'm wrong I hope someone else can help.

 

[airshot]

Check your head for flatness, the 3.0 are noted for there heads warping if overheated. Had to do mine a few years back when a belt broke. You have it apart anyway, so fix it right. Check the block as well with a good straight edge, normally the head but blocks have been known to warp as well. Good luck !!

 

[Troubled1]

Check your head for flatness, the 3.0 are noted for there heads warping if overheated. Had to do mine a few years back when a belt broke. You have it apart anyway, so fix it right. Check the block as well with a good straight edge, normally the head but blocks have been known to warp as well. Good luck !!

I dropped the head off at the machine shop. They’ll check the valves, replace the cracked valve and resurface the head.

 

[Troubled1]

I decided while waiting for the cylinder head to check the impeller. It is actually intact and not hardened. Unfortunately, the gear on the shaft behind the impeller has a couple broken teeth and the gear it drives needs new bearings as they are hard/rough to turn. The price of these gears (even used) has me considering pulling all the stern drive components and going to an outboard setup.

 

[Troubled1]

I found an NOS gear on eBay and it’s all back together. The machine shop only charged $100 to replace the valve and resurface the head. I took it out on the lake and no overheating!!

The new problem is run ability. It fires up quickly then pretty much immediately dies. It takes several attempts to finally stay running. Dwell set at 30° timing at 6°. I think the problem is in the fuel delivery. If I hold the choke flap partially closed, I can keep it running and it seems really smooth. I’ll try adjusting the automatic choke and then the idle mixture. Hopefully I can get things dialed in.

 

[dubs283]

That's a good price for a machine shop. Hopefully the work is sound

Holding the choke partially closed to idle proper indicates a lean issue. Not enough fuel or too much air. Could be carb is plugged/junked up and need of rebuild

Low fuel pressure caused by a weak pump or restriction, vacuum leak. Could even be water ingestion from a failing exhaust system

Guessing the head failed due to this earlier, need to rectify otherwise you'll hurt the head, valves and gasket again

 

[Troubled1]

So far I really haven’t had a lot of time to work on it. I’m leaning toward fuel delivery as I’m not sure how old the fuel filter on the pump is. I picked up a new filter which I’m hoping to replace today. I also picked up a rebuild kit and if the filter and adjustments don’t help, I’ll take the carb off, strip it down and bring it to work and run it through the ultrasonic cleaner (I work in an aircraft maintenance facility) make sure all passages are clear and then put it back together. I’ll also double check the dwell and timing while I’m at it.

After cleaning and having the machine shop soak my manifold in their engine tank, I’m pretty confident that the exhaust isn’t the issue. So far all the issues seem to be at low rpm. Poor idle/stalling, hard starting. Worst case I’ll run a carter electric fuel pump and a remote spin on filter/water separator. One other thing I need to double check is the valve adjustment. Hopefully I can figure it out this weekend.

 

[dubs283]

10 minutes max at top temperature in the ultrasonic cleaner. Dish soap that saves baby duckies is the best emulsifier. Then go through every passage in the carb, nice and clean. Buy a decent brand rebuild kit, preferably oem

Get the valves adjusted proper first, then focus on fuel delivery

 

[Troubled1]

I already have the carb kit (Napa) the ultrasonic cleaner I’m using at work will be the one used for turbine fuel system components. I’ll run it through a short cycle then inspect it. It would be nice if the problem was something simple like a low float level but if that was the case, the higher speeds would suffer as well. I’ll pick away at it and I’m sure I’ll get it back to where it’ll run reliably.

 

[Troubled1]

I disassembled the carb and it wasn’t pretty.

The first photo is the fuel inlet filter, the second is the fuel inlet and finally the fuel I sucked out with a large syringe. The murky stuff at the bottom is dirt and water I ran the carburetor through 2 short cycles in the ultrasonic cleaner, blew everything out, used aircraft safety wire to clean out passages then another quick cycle in the ultrasonic cleaner I reassembled the carb going by everything the instructions called for. I’m feeling more optimistic now.

 

[dubs283]

Based on the amount of debris in the inlet filter I'd be suspect of contamination/debris in the fuel tank/failing filter(s)

 

[Troubled1]

I’ll be at it again this weekend and figured I best leave the fuel line disconnected and crank the engine to pump out a cup of fuel into a clear container and check for water. I ordered a water separator kit and will also get that installed this weekend. I also have a new filter to replace the one that is mounted to the fuel pump. Definitely filthy considering I stripped it down 2 years ago and cleaned it at work and put a kit in it.

 

[Troubled1]

One thing I need to ask those in the know. Is that annoying low oil pressure buzzer somehow interlocked to cut out the ignition if low oil pressure is detected? I’m asking because some of the diesel GPU’s we have at work have a time delay on the oil pressure. It’ll run for a few seconds then shut down if oil pressure drops below a certain threshold. I disconnected the one in my boat because it drove me crazy when trying to get it started. Gotta cover all the bases.

 

[Troubled1]

I tried adjusting the valves yesterday, didn’t work out. I had it running up to temp and it would barely idle. Dwell at 32° timing at 6°. When I backed off the adjuster nut until the rocker clattered (#4cyl) the idle picked up and was smooth as silk. I slowly tightened it down 1 turn and it would barely idle even after several minutes. I’ve never had an engine do this before.
Any suggestions? Should I just put it to tdc on #1 and do the adjustment as per the manual? Is there something I missed?
Anything above 2000rpm its smooth. Anything below that it runs rough.

 

[dubs283]

Stuck lifter? Wrong pushrod/spring? Bent rocker? Tuliped valve?

Are all the other valves sound and set proper?