Gravel in 1988 mercruiser 4.3l l4 water drains.

[Littleg15uk]

Engine ser no 0B901968 mercruiser 1988 4.3l
Towards the end of last season the river level was low and we bottomed out. After that engine would overheat at low revs.
Gave up for year and winterized it. When draining engine I discovered that all four drain plugs were blocked with fine gravel which I poked and the water then gushed out
This year I replaced all the water pump parts in the sterndrive as well as the impeller. Ran the engine with muffs on and all seams fine. Just for piece of mind I undid drains again and once more they were full of gravel. Cleaned out again and left them out and ran engine again with muffs on to try and flush the rest out. Now the boat is back in the water and running fine but each time the engine has cooled I pull the drains again and they are still full of gravel.
Can anyone suggest how I can get the rest of the gravel out and anything else I should check?

I have a manual for the sterndrive but not the engine and I cannot work out which is the right one for this model so some help with this also would be appreciated.

Thanks
Littleg15uk

 

[Bondo]

Re: Gravel in 1988 mercruiser 4.3l l4 water drains.

Can anyone suggest how I can get the rest of the gravel out and anything else I should check?

Ayuh,... Welcome Aboard,... Just keep doin' what yer doin',... it a perpetual problem,...

Mine is always loadin' up with silt, sand, 'n rust,... it's the nature of raw water coolin',...