ForeverDrivin

So, I got a 1998 Mustang V6 that went through a huge puddle that was hiding just around a bend, and since I dont have a passenger wheel well guard, it got all in my intake and the engine "hydrolocked" at IDLE and died very slowly, there was no large *clunk* or anything like that. Turned the key a couple times and I guess I burned out the starter when it happened, so I put a new one in and everything clicked off, thought it could also be the battery so I hooked up my Aspens heavy duty battery as well. Turned the key and made this noise: https://drive.google.com/file/d/19Y6xD9uXVtjcpXyRa_fTq0Uei0K0z7Z6/view?usp=drivesdk

IMPORTANT INFORMATION: The car RUNS fine. We purged it and managed to push start the car and I've done it many times to get it back into the garage and such. The car runs just like it used to. I've had a lot of people say it's a trainwreck now but they all suggest broken/bent connecting rods or blown compression but the car RUNS. I've pushed it as well on a test drive and everything seems in order.

Any suggestions? I've got it in the shop now but probably wont hear back for around a week so I'm curious as to everyone's diagnosis.

Derf00

Compression test, followed by a leak/down test, then let us know how 'fine' everything is

Hydrolocking causes damage. Either water in the oil that affects lubrication or something getting bent because water does not compress. Running the two tests above will check the engine internals for damage and what type of damage.

ForeverDrivin

Everyone references the bent connecting rods and stuff like that, but they never really answer the question: why will it run but not start? I just need the thing to start itself for a while longer until I grab a new car or engine. It runs exactly as it did before, and I'll be checking the oil once I get the car back for any contamination.

Well luckily I have a mechanic on it now anyway 🙃. Either way, the engine is ****. The AC compressor went from the auction house overfilling it to make it blow cold, fuel gauge doesnt work, and the tranny has some chatter to it. I just bought some new suspension for it to and I had to replace the outer tie rods because both ball bearings were in half. Luckily everything I've bought for it transfers to a different GT when I get one.

Derf00

Does the starter actually engage the flywheel and spin the motor? It's possible that it's stuck in place and will spin but not not extend the bendix gear to engage the flywheel.

ForeverDrivin

It was a bad battery wire and damaged gears on the flywheel

Derf00

Thanks for reporting back, glad you found the problem.

To answer your other question about runs but struggles to start or won't start without help. It's physics. Mass (pistons/crank/flywheel (and frictional forces etc) + Force (Starter and combustion force) = motion/work/acceleration (rotational momentum of engine)

Your engine firing up is a combination of starter force and combustion (firing) force to get the rotational momentum going.

Cars with low compression can seem to run ok because the momentum of the other cylinders firing helps the engine maintain it's rotational momentum (motion/work).

Low compression means that energy from the combustion cycle of the motor is lost/leaked. This reduces the amount of combustion force available to get the engine rotating on its own and increases the amount of external (Starter) force needed to get that rotational momentum going.

Depending on how big that motor is and how many cylinders it has, the engine could sputter out before it gets enough inertia from the starter and reduced combustion force to catch.

Sometimes it will simply require a slight longer crank time or additional external energy to get the engine rotating. Starter fluid has a much higher energy potential than gas so spraying that into the intake while cranking can help make up for some or all of the combustion energy lost. Thus it fires up, but only with the help of starter fluid.