Exhaust Manifold broken bolt removal _ boat runs hot at high speed

Mike_Maranto · Apr 26, 2011

Hi. I have a 1995 Crownline with 5.0 engine, my boat runs hot at high speed, at low it is fine, I replaced the risers and the impeller. It still runs hot, my next step is to replace the manifolds. While removing the manifold I noticed one screw has no head, any suggestions what I should do? Can I cut the with cutter the manifold and the remove the manifold and remove the stud using wise grip? Any help is appreciated.
Also with heating am I moving in right direction??

twostroke87 · Apr 26, 2011

Re: Exhaust Manifold broken bolt removal _ boat runs hot at high speed

The 5.0 uses 4 long bolts that thread into the engine, not the manifold. So if you can remove the other 3 bolts, and slide the manifold over the broken bolt, if there is even anything to slide it off of.

You'll find either a long broken bolt thats threaded into the block that you can try and work out with some heat, spray oil and vice grips, or you'll find the bolt snapped right at the engine.

Go from there.

Mike_Maranto · Apr 26, 2011

Re: Exhaust Manifold broken bolt removal _ boat runs hot at high speed

Thanks that is exactly true I took out the 3 long bolts and the forth one probably I will need to scrap off the remaining head. Usually the manifold comes right off or do I have to hit with a rubber mallet like I did with risers?
Also you think I am in the right direction with heating issue?
When I replace risers should I go with closed gaskits or open ones (four open slots)
( the original ones were the closed ones//two slots open)......much apreciated

twostroke87 · Apr 26, 2011

Re: Exhaust Manifold broken bolt removal _ boat runs hot at high speed

Are you on the right track? Sort of

You made no mention of changing the thermostat. Also, when you replaced your imepeller was it missing any of the rubber veins? If it was they might but up in the cooling system, somewhere between the raw water pump you replaced and the thermostat.

So...change the thermostat for sure.

and yea, next is risers and manifolds. The manifolds usually have a decent about of rust that creeps around the gasket sticking the manifold to the engine, a couple of well placed pry's should pop it loose.

Yes, you want to use the gaskets on the riser with the 2 open slots and 2 closed. If you want to be absolutely sure, find out using the serial number of your engine what you need.

Mike_Maranto · Apr 26, 2011

Re: Exhaust Manifold broken bolt removal _ boat runs hot at high speed

I change impeller every season, the impeller was ok, I have not changed the thermostat but I thought with thermostat the boat heats up at low or high speeds. Is there a way to check how good the impeller is pumping water, I heard some mentioning of taking a hose off some where around thermostat....?

cr2k · Apr 26, 2011

Re: Exhaust Manifold broken bolt removal _ boat runs hot at high speed

Yes the hose that runs back to the transom shield, may also go thru a heat exchanger to cool the PS fluid. Pull off thermo housing. Best to put a short section of clear tubing in there so you can see what is going on underway.

Mike_Maranto · Apr 28, 2011

Re: Exhaust Manifold broken bolt removal _ boat runs hot at high speed

Upon cleaning and scrapping the bolt without face, I learned it was welded to the manifold, now I need to find a way to cut through the manifold, either through the bottom up or some other way....very upset why people do cheap stuff....have heard or read how some one dealt with problem like this??

Bondo · Apr 28, 2011