My white 87- 300TD hydrolocked... gotta replace the head, or engine? - PeachParts Mercedes-Benz Forum

vstech · #1 06-26-2023, 10:06 AM

Ok, I have a spare car with a #22 head installed... but it's a lot of work to swap engines.
I'm trying to decide if I should try to swap headgasket, or find another #22 or try and repair what I have...

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dieselbenz1 · #2 06-26-2023, 11:49 AM

Yikes, I would think rod and bearing problems in addition to head issues. Were you working on the car at the time?

87tdwagen · #3 06-26-2023, 12:58 PM

Bummer.
I would say, pull the head, inspect the damage and then decide. You might get lucky, and if not, you're partially there on pulling the engine anyhow, so not much lost.

Best of luck

t walgamuth · #4 06-26-2023, 02:53 PM

I believe in our long rod bender thread we found that most bent the rods and possibly twisted the piston. If the rod is not bent too much the engine will run and idle but will show a minor skip in the exhaust note. As the rod is bent it twists in the piston making the piston no longer perfectly parallel with the center line of the rod. lt lowers the piston in the bore a bit and the bent skirts will rub on the walls. I'd start the engine up and see how it runs. If it does not skip I would probably use it.

vstech · #5 06-26-2023, 03:13 PM

Nah, I've known the head was weak for a while now, it has needed topping off of coolant monthly...
It was parked for a few days, and went to start it, and nope...
Hose was under pressure, I suppose the coolant just filled the cylinder and now it won't turn over.
So...
I COULD pull all the glow plugs, spin it over and get it unlocked, then keep driving it until I destroy something...
Or park it, and deal with it asap...

vstech · #6 06-26-2023, 03:16 PM

I'm actually at the Mercedes dealer at the moment dropping off my new to me 2011 sprinter for the AEM emissions recall rebuild...
They tell me it will be a few weeks to complete...
Ugh, I just started getting the van organized the way I need it...
Had to strip everything back out of it and cram it all into my old van...
Ugh.

vstech · #7 06-26-2023, 07:14 PM

Well after letting it sit a few days with the pressure released on the cooling system, the coolant must have finally drained out of the cylinder, because it started fine today.
I will release any pressure when I drive it, but I'm pushing my luck with the car for now...

87tdwagen · #8 06-26-2023, 08:29 PM

Although I don't promote quickie fix products, maybe some Bar's Leak head gasket repair will buy you some time before properly fixed.

vstech · #9 06-28-2023, 09:54 AM

Idk,I really wanna fix this right, and I figure this stuff in the cooling system could just make it hard to repair going forward.
Won't matter if I replace the motor, but if I decide to replace the head it could be messy...

ah-kay · #10 06-28-2023, 11:24 AM

You noticed engine won't start and suspected it was hydrolocked? It is coolant seeped into the cylinder(s). You would hear a 'dud' sound and engine wouldn't turn over.

The starter wouldn't damage the rods or pistons. It doesn't have enough torque or power so the engine is fine. The car started fine after a few days is because coolant drained down to the sump. Just replace the head, engine will be fine. Next time no start with a 'dud' sound, remove the injectors and spin the engine. I bet coolant will squirt out. BTDT.

t walgamuth · #11 06-28-2023, 11:42 AM

In that Rod bender thread we decided it originated with a leaky head gasket. As the gasket fails it will allow seepage into the combustion chamber, first a little then more until there is a problem. A small amount of coolant can bend your rod just a little so it will run and start. Enough coolant will bend the rod. It can bend it just a small amount and it will run with a skip. Also I remember after discussing it with my machinist I did a calculation and convinced myself that the starter does provide enough power to bend a rod.

ah-kay · #12 06-29-2023, 11:17 AM

Quote:

Originally Posted by t walgamuth

In that Rod bender thread we decided it originated with a leaky head gasket. As the gasket fails it will allow seepage into the combustion chamber, first a little then more until there is a problem. A small amount of coolant can bend your rod just a little so it will run and start. Enough coolant will bend the rod. It can bend it just a small amount and it will run with a skip. Also I remember after discussing it with my machinist I did a calculation and convinced myself that the starter does provide enough power to bend a rod.

Please share your calculations. The starter has so much Kwh power?

t walgamuth · #13 06-29-2023, 04:45 PM

I don't have them at hand or perhaps anywhere.

There is a lot of mechanical advantage from a starter to a flywheel. The mechanical advantage of 8 or nine teeth compared to 70 or so on the flywheel gives a lot of power.

The key perhaps is the weight of the crank and all other attached parts slamming a piston into a cylinder at nearly the top of its stroke.

If the engine started up and fired on a cylinder or two would you agree that is enough to bend a rod?

ah-kay · #14 06-29-2023, 09:28 PM

Quote:

Originally Posted by t walgamuth

I don't have them at hand or perhaps anywhere.

There is a lot of mechanical advantage from a starter to a flywheel. The mechanical advantage of 8 or nine teeth compared to 70 or so on the flywheel gives a lot of power.

The key perhaps is the weight of the crank and all other attached parts slamming a piston into a cylinder at nearly the top of its stroke.

If the engine started up and fired on a cylinder or two would you agree that is enough to bend a rod?

What goes in, will come out. Starter on average draws 200-400A for 15sec ( or however long you spin it ). Assume 400A. The kwh produced will be 400A x 12V x 15s / 3600 / 1000 kwh = 0.02kwh. This is the energy produced to spin the starter for 15sec. Enough to bend the rod?

t walgamuth · #15 06-29-2023, 10:27 PM

Quote:

Originally Posted by ah-kay

What goes in, will come out. Starter on average draws 200-400A for 15sec ( or however long you spin it ). Assume 400A. The kwh produced will be 400A x 12V x 15s / 3600 / 1000 kwh = 0.02kwh. This is the energy produced to spin the starter for 15sec. Enough to bend the rod?

What is that in ft lb?

View Poll Results: What would you recommend?
Swap in engine	2	40.00%
Find another #22 head and repair, keeping stock block.	1	20.00%
Pull head, replace gasket and keep entire engine stock.	2	40.00%
Voters: 5. You may not vote on this poll