Panther Marine 7.4l Won't Start

[laserbrn]

Instead of continuing to start multiple threads with information about specific topics as I search for why my engine won't start, I figured it best to just provide all of the information that I have and beg my friends at iboats to help me through this.

This engine was run on old gas a few weeks ago. It did run smoothly for about 3 hours while the previous owner was shooting a youtube video to help with the sale of the boat.

Engine Specs as I know them (limited information, so bare with me):

7.4l from around 92-94 from Panther Marine Engines

Volvo Penta 280 outdrive

Holley 4 barrel Carburetor - Cleaned and rebuilt

New Distributor Cap/Rotor

New Spark Plugs

New Park Plug Wires


When I checked out the boat originally I could not get it to give me good compression readings. When the starter is cranked it doesn't seem to always have compression. At times it would read zero and I'd give up on it only to find later the compression on the same cylinder was 120.

I borrowed a compression gauge from Autuzone just in case mine was broken and I got the same results. I through my hands up after awhile and told the owner that I wasn't interested in the boat as it wasn't running and the compression tests were wonky. He said make me an offer, we agreed on a price and I am trying to get it to start for the big win. I'm losing optimism, but I'm not ready to throw in the towel yet.

The boat is in a slip right now and I picked up a trailer today so that I can haul it out and work on it my driveway.

Here's what I've done:

I took the carb off, took it down to a carburetor shop and had them rebuild and clean it. I removed all of the old gasket material and reinstalled the carb. I used pictures from my iPhone to ensure all of the connections went back in the original places.

I plugged a spark plug into one of the spark plugs and cranked the engine....no spark. I pulled the coil wire off the distributor and cranked the engine with a screwdriver near it and I couldn't SEE the spark, but can hear it and feel it. It might be a little weak though as it didn't really arc and 'tack...tack....tack...' wasn't very loud.

I replaced the distributor cap, rotor and all of the spark plug wires. I cranked it over and it did not start. I ran out of time as I had to meet a guy to buy a trailer to get this thing out of the water. I didn't get a chance to test a spark plug and crank it over as I also didn't have anyone around to help out today and I can't reach the ignition from anywhere I can see the plug wire and hold it up out of the bilge where it's a little safer.

I know I really haven't given myself any definitive answers. I need to do thorough compression test again and I'll post the results. I need to determine if the spark is strong and firing the plugs. I should have those answers soon. I'm going to haul it home hopefully on Wednesday.

Oh, I have been running it on fresh gas from a small tank, not the bad gas in the main tank. I've tried spraying a little starter fluid, but no go. Just cranks and cranks.

Thanks in advance and to those that have already helped in my previous threads.

 

[Don S]

Re: Panther Marine 7.4l Won't Start

You do not have a Volvo, so moving this thread to the Other Brands of I/O & Inboard Engines & Outdrives forum.

 

[laserbrn]

Re: Panther Marine 7.4l Won't Start

You do not have a Volvo, so moving this thread to the Other Brands of I/O & Inboard Engines & Outdrives forum.

My apologies. I assumed any engine with a volvo outdrive would be under the "volvo" application and grouping. I suppose as this is specifically an engine related question this section makes sense. I'll try harder to be more discerning. Too many long days in the sun.

 

[kmarine]

Re: Panther Marine 7.4l Won't Start

From your description I believe your problemb may be in the pionts or condenser if you have this type of ignition. Otherwise a weak pickup coil or main coil. I am not sure What type if distributor you have, but I would start there. There is also a possibility of a defective tachometer or wire grounding out the ignition wire or a ignition switch. Doubble check these.

 

[Bondo]

Re: Panther Marine 7.4l Won't Start

When I checked out the boat originally I could not get it to give me good compression readings. When the starter is cranked it doesn't seem to always have compression. At times it would read zero and I'd give up on it only to find later the compression on the same cylinder was 120.

Ayuh,..... Did you remove All the spark plugs, 'n move the throttle to Wot,..??

I took the carb off,

So does the carb spray fuel when you pump the throttle now,..??

I replaced the distributor cap,

You still haven't told Us WHAT Ignition you have,.. Are there Points under that cap,..?? Electronic,..?? Who's,..??

and I can't reach the ignition from anywhere I can see the plug wire

Get yerself a remote starter button, 'n a jump wire for the ignition...:facepalm:

 

[laserbrn]

Re: Panther Marine 7.4l Won't Start

It's an electronic ignition, no points. I replaced the module and BAM, spark. That problem is solved.

BUT,

I pulled the valve covers....6 broken pushrods and 2 bent ones. All on the intake side. The theory I have so far is that the motor ran fine on the bad gas, when it stopped it cooled and gummed up. Sticking valves and gummed out valve train led to broken pushrods. This is BEST case scenario.

Worst case scenario....the sticking valves led to fuel in the cylinders, cranked it trying to start it and broke the pushrods. If this is the case it could have also bent a rod. I will be back down there this weekend and I'll pull the intake off and see what the deal is.

Hopefully new pushrods, a good cleaning and all will be well. My buddy is going to bring his bore-scope and some other tools on Saturday and we'll take a look into it and hopefully she'll run again. Everything under the valve covers looks really clean and it looks like its in really good shape so we'll see.

 

[Bondo]

Re: Panther Marine 7.4l Won't Start

BUT,

I pulled the valve covers....6 broken pushrods and 2 bent ones. All on the intake side. The theory I have so far is that the motor ran fine on the bad gas, when it stopped it cooled and gummed up. Sticking valves and gummed out valve train led to broken pushrods. This is BEST case scenario.

Ayuh,... I don't see that 1....

Worst case scenario....

Worser Worst case scenario,.... Water from the exhaust caused the hyd-lock....

Pull the risers, 'n have a peek....

 

[laserbrn]

Re: Panther Marine 7.4l Won't Start

That's not really any worse...bent rod, slurped salt water, same thing...motor is toast.

I had a guy check it out today and he confirmed, intake valves are stuck. He's soaking them in pb blaster and he'll try to get them free, but the reality is, it needs at least a valve job, and this motor was questionable as I just bought the boat.

I'm going to repower....now I just need to find out what my best options are for that. To rebuild, or buy something else...that is now the question. I'd like to use the same style BBC as it is all setup and I don't want to have to fab up a bunch of things. The current exhaust setup is through hull and everything is all lined up and the boat should move along nicely with one of these in working order.

I'll get the boat home and decide what I want to do.