Badly overheated Volvo MD6A....now no compression??

[jeffjd]

Good luck! With your trip and rebuild.


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[Cadence]

Originally Posted by Sur la Mer

After cleaning out the Marvel and removing some carbon from the very top of the cylinders I found one small spot where seizure had occurred one one cylinder. The other leaked down slower but did it did leak and had a bit of scuffing near the top (hard to see). Since I was there and had nothing to lose (key gaskets carefully reused/sealed, secondary gaskets 'made' with RTV) I went ahead and reassembled the motor then tried to start it. Under continuous cranking it spit a few times. I can feel better compression when turning the flywheel by hand, but clearly it's not enough so the motor needs rings. (Hpeer - I originally hoped the rings were only stuck and that the Marvel would free them up). Since that rebuild'll be a long term project I'll order proper gaskets with the rings and rod bolts (Thanks hellosailor. What are these shims of which you speak, Cheeechako?) If I find better than list pricing I'll post the source for the group...and I'll start another thread for rebuild Q&A.

As for my upciming boat move I've started tuning my old 15hp Evinrude long shaft, purchased a motor mount, and made sure my cell phone and VHF are set to Seatow's contact info.

Thanks to all who reponded!

Please post the outcome of the move.

[model 10]

If you put it back together correctly, bring along a can or 2 of starting fluid. Set the throttle (fuel control) in about the low middle somewhere. Start cranking and give it a shot. You won't need any compression. Keep the thing running at a good clip and it will just be another smokey old engine needing a rebuild.
You don't have a glow plug? If you did, it would help.

[gjordan]

Sur la Mer, There is nothing in the overhaul manual about the rod bolts being stretch bolts that have to be replaced at every removal. It is a good idea to have them checked with non destructive testing, which I think would be far less expensive than Volvo prices for 4 bolts. There may be other model Volvos that use stretch bolts, but not the MD6. Good Luck. ______Grant.

[Sur la Mer]

I will definitely try the starting fluid before I haul the boat next week!!! No glow plugs.

Great to know about the rod bolts! I hadn't seen anythign in the manual either, but hadn't really had time of late to research the issue.

I posted another thread about the delivery regarding how to mount an outboard on a countered transom. I bought a 9.9hp Mercury Bigfoot 4-stroke, bought an aluminum articulating mount with 16.5" of travel and fabricated a temporary mount to get the prop into the water. We got her to her new home in Nyack in 22-hours over two windy days with a couple hours of sleep in City Island. Took the East River at slack water - no issues. Outboard stayed attached () but reaching the front-mounted controls is hardly convenient so it's not a permanent solution without adding remote controls to the outboard (and painting the steel mount, obviously). I'll rebuild the diesel then take this thing off. See pics of the mount, boat alongside the City Island Yacht Club dock Sunday morning and the boat alongside the Nyack Boat Club dock Monday evening. Bonus shot of the Freedom Tower from the Hudson River. Amazing trip. Highly recommended.

[Cadence]

Originally Posted by Sur la Mer

I will definitely try the starting fluid before I haul the boat next week!!! No glow plugs.

Great to know about the rod bolts! I hadn't seen anythign in the manual either, but hadn't really had time of late to research the issue.

I posted another thread about the delivery regarding how to mount an outboard on a countered transom. I bought a 9.9hp Mercury Bigfoot 4-stroke, bought an aluminum articulating mount with 16.5" of travel and fabricated a temporary mount to get the prop into the water. We got her to her new home in Nyack in 22-hours over two windy days with a couple hours of sleep in City Island. Took the East River at slack water - no issues. Outboard stayed attached () but reaching the front-mounted controls is hardly convenient so it's not a permanent solution without adding remote controls to the outboard (and painting the steel mount, obviously). I'll rebuild the diesel then take this thing off. See pics of the mount, boat alongside the City Island Yacht Club dock Sunday morning and the boat alongside the Nyack Boat Club dock Monday evening. Bonus shot of the Freedom Tower from the Hudson River. Amazing trip. Highly recommended.

Grats! Thanks for the feedback.

[gjordan]

Just as a point of information, I have checked, and compared the exhaust manifolds from my MD6B, and my MD7A, and while not identical, they are interchangable. You would have to have the proper thermostat housing for which ever manifold you used, and the water hook ups are a little different, but easily adapted. On another thread there was mention of $1500, for a custom made manifold, so if you can find a used manifold for a decent price, it will work on either engine. Maybe this will help someone. ______Grant.

[Sur la Mer]

Hey Grant,

If I had to replace the manifold I'd transfer the gasket hole pattern onto 1/2-inch steel plate. I'd drill them out then tap them to the next size up FNPT size (1 or 1.25" for exhaust, 0.25 or 0.375 for cooling). I'd screw black steel nipple into each hole then build using standard fittings. If I had to butt weld a custom fitting or two or transition to copper for the cooling then its no big deal. Easy to add zinc, flush and temp sensor ports. The thermostat would take some thought (orifice plate union maybe?), but total cost would be under $150 If I build one I'll take a pic.

[gjordan]

I was cleaning, and sand blasting the 6 manifold today, and I now know what Hellosailor meant about a rock blocking the bypass passage. This on has some kind of bolt in the passage and the thermostat was completely corroded away. I wonder how many Volvos never run at the proper temperature? The $1500 manfold I mentioned was made of stainless steel, and I had always thought that exhaust gas,s , salt water and SS did not mix well. Maybe I have been wrong? ______Grant.