Mystery Merc problem

[jimp37]

Hello all - Have a problem with a 2001 20hp Mercury. The motor will only start with the center bolt of the exhaust manifold cover fully loosened.There are 9 bolts holding this cover on.I noticed the center one was loose,so I tightened it while it was running and it stalled.Loosened it and it started up again.Nobody seems to know what the problem is.Also,I saw a trickle of water come out from the gasket of the manifold cover.I tightened it and it seemed to stop.Is water supposed to circulate through there? I'm guessing that when I took the cover off last month and put it back on I didn't tighten it enough.Anyway , at this point the motor will only start with full choke on and the center manifold cover bolt loosened.Model # is 1020201YD. The part number I'm refferring to is # 43 on Mercury's parts express website.There are 9 bolts that hold that part on and I think the bolts actually hold the manifold itself on as well{not sure}.I did a compression test =Top cylinder at 107 ,bottom at 104

 

[Workshopmonkey]

Re: Mystery Merc problem

The compression looks good but this is only telling you whats happening as the cylinders aprroach TDC cos the gauges have one way valves. Is the bolt you've loosend leaking gas so relieving pressure. Underneath this cover are your exhaust ports for the cylinders and the pathways for the cooling system. Remove cover inspect the edge of your cylinders and check the gaskets make sure you've got good seals al round and replace the gaskets when reassembling, make sure you torque this plate up correctly as gas leaks here will mean to much air and the engine will be lean unless it's got the choke on

 

[jimp37]

Re: Mystery Merc problem

Nothing leaking from the bolt hole.No water or gas on the bottom of the cowl.What do you mean when you say "cylinders approach TDC "?

 

[jimp37]

Re: Mystery Merc problem

Bump