88 mercury black max 200 cylinder wall help

[cjlallo]

I have a 88 mercury black max 200 I got last season and it would always run hot at higher rpms 2500 or so. I replaced the water pump thermostats and poppet valve with very litle change. I recently pulled the heads and exhaust divider plate thinking I probaly had a lot of corporation built up our a head gasket issue. well it turns out theres very litle corrosion or build upand its much cleaner inside then I thought.but what I found is theres very tiny holes in the cylinder walls and on the heads in the spherical area where the spark plug goes. The holes in the cylinder walks dont go all the easy through the wall and aluminum but there are a few that appear to go past the sleeve. I don't think these have anything ti do with the over heat issue but what are this holes from most are pin sized. Thanks guys.my other question is it okay to mill the heads a couple thousandths to get a go od clean mating surface and how much can I safley take off without any issues.

 

[CharlieB]

Re: 88 mercury black max 200 cylinder wall help

The pin holes in the cyl do not go all the way thru, leave them alone and forget about them.

If you look closely at the last pic on the left two cyl sealing surfaces at the 3 o'clock position you should notice the blackening, indicating the head gasket leaking cumbustion gases into the cooling jacket, overcoming the water pump pressure, displacing water and allowing the motor to over heat when the throttle and load increases much past an idle.

Do you check the compression before pulling the heads off? I would expect it to have been in the area of 120 psi.

You can mill the heads and increase the compression to make a noticeable increase in power output but you do NOT want to increase compression greater than 145. Even at 145 you would be well advised to use 91 gas. I've lost all my links to a hard drive failure so I can't give you more direction except it is safe to mill 5 to 10 thou without raising compression a dangerous amount.

 

[Faztbullet]

Re: 88 mercury black max 200 cylinder wall help

The pin holes are there from the casting and chroming operations and will not hurt anything if fact they may help as they will hold a little extra cylinder wall lubrication. The darkening I see looks to be oil/fuel running out of cylinders at would be the 6 o'clock position if looking at motor or 3 o'clock on pictures. You can mill the spherical "hemi" heads .020 and only raise the compression 2-4 psi due to the fact the head gasket in nearly .060 thick.

 

[cyclops2]

Re: 88 mercury black max 200 cylinder wall help

I enlarged the last picture by 150% & 200%. The extreme right edge of all 3 cylinders has a well advanced condition of corrosion of the Aluminum block walls. The brown looking stuff is " cooked " Aluminum wall. That fits in with the no black carbon area right where the spark plug ignites the mixture. The head gasket is sealing on the " pressed in metal sleeves. it is seen as a ring on the edge of the sleeves.

Pictures make the block look like crap. BUUT If that corrosion DOES NOT get past the pressed in metal sleeves. You are OK on compression. I would VERY VERY CAREFULLY scrape all CRUD off ALL surfaces of the cooling passages. Same for the head. Could be a pile of wall bits partialy blocking the flows. Also possible the " CRUMBS " have worn out the rubber water impellor or blockd up those passages.
WHOA ! Just reread you saying the holes DO GO PAST THE sleeve. ....BINGO That is your hot gas leak path into the water system above 2500 rpm.

If you DO PULL the block apart for a sleeve change. WASH OFF ALL oil on any 2 pieces that go together. Then put a wide felt tip # on the 2 mating surfaces. That is a foolproof way to take apart & reassemble EVERYTHING. Bolts, nuts, bearing rods, bearing 1/2s .......EVERYTHING HAS MATCHING NUMBERS...before you take them apart.......... no exceptions !!

You have some work ahead of you. Good luck.
BAD, BAD. Not sure if that engine has a wall worth resleeving. You need to have a shop press out the sleeves to see the corrosion extents.

MAYBE.....You get lucky with a NEW set of no hole sleeves. & you are good to go WOT.

EDIT

Tell the machine shop THEY MUST not remove those # you put on .UNLESS THE CAN scratch or etch the numbers............Better Take plenty of pictures of the block # locations. Remark it if they forget. Good chance they will.

 

[cjlallo]

Re: 88 mercury black max 200 cylinder wall help

Well I obviously got a few different opinions from you guys. Cyclops, the pin holes in the cylinder walls do nott pass into the aluminum but only the one big one. But it definitly does not go through the aluminum that the sleeve is pressed into and on the back side of where that hole would go in the water jacket side has very litle corrosion only on the surface so how did those holes get there because they did not come there from the water jacket side and how would thaT cause an overheat condition if there not passing into the water jacket. Thanks so much guys

 

[cjlallo]

Re: 88 mercury black max 200 cylinder wall help

O and compression was aprox 110 on all cylinders

 

[Faztbullet]

Re: 88 mercury black max 200 cylinder wall help

The head gasket is sealing on the " pressed in metal sleeves. it is seen as a ring on the edge of the sleeves.

Uh no....this engine does not have sleeves,:facepalm: it is a aluminum bore that is chrome plated thus the pin holes that where there from the factory when assembled. cjlallo just true the heads and install new head gaskets and you will be good as that block does not need any work to it.......

 

[cyclops2]

Re: 88 mercury black max 200 cylinder wall help

Well I did you a favor.
I called my local mercury dealer for a decision on the sleeving. His top mechanic said based on the age & the sharply defined circular rings around the bore. It sounds like someone had a boring out & the installation of sleeves & oversized pistons done already.
He said to be sure. Take clear pictures & or the engine / block to a dealer for a positive answer. he said there is a lot of work to be done, if repairable.

Call your local Black Max dealer.

 

[Faztbullet]

Re: 88 mercury black max 200 cylinder wall help

Hate to disagree with ya but that engine aint been bored or sleeved on the pics he has posted as you can see the chrome plating You can tell if a chrome bore has been resleeved big time as it stands out like a sore thumb. Trust me as I have built and raced a ton of old 2.4 blocks.....

 

[cyclops2]

Re: 88 mercury black max 200 cylinder wall help

Hope fully cjlallo will post back on the crappy appearence of the walls. I can honestly say that is the worst walls I have EVER seen or even heard of. Including car, aircraft, sewer & waterpipes. Unreal crap job by someone.

Good luck on this repair cjlallo.

 

[Faztbullet]

Re: 88 mercury black max 200 cylinder wall help

I can honestly say that is the worst walls I have EVER seen or even heard of

Car and aircraft use a cast iron liner but this engine does not. The 1979-91 175 & 200hp 2.4L are the only one made this way as it was a way to make the enginea tad lighter and run cooler. The posted pictures is the standard appearance of a chrome bore block as it is a chrome plated hole. Next time your by a repair shop stop and ask if they have a old block laying around you could inspect and you will see the pin holes in cylinder walls along with the plating. You have to run a special piston ring in this bore due to the plating

 

[cjlallo]

Re: 88 mercury black max 200 cylinder wall help

hey guys thanks so much i really apreicate all your info. cyclops thanks for going out of your way making that phone call for me. so cyclops whats your opinon on the pin holes the definitly did not corroded from the water jacket side into the cylinder. so how did they get there? also how do you think they are the cause of my overheat if they dont enter the waterjackets? basicly because i have already invested more money then i ever planed into this boat. i am going the mill the heads a couple thou and reassemble and see how it runs. before i took it apart it ran great and had good compression just would run hot at like 2500 and if i let of the throttle it would drop right back down. i cant afford a rebuild so i have to try this and if it dosent work il unfortuntly have to be done with it.

 

[cjlallo]

Re: 88 mercury black max 200 cylinder wall help

hey fazt does the spheircal "hemi" portion of the head also have chrome or some kind of lining on them or is that just bare aluminum? becuase theres actully a few very very small pin holes there too. not that im concerened with them just wondering how and why they are there.

 

[cyclops2]

Re: 88 mercury black max 200 cylinder wall help

Lets go to the heart of the overheat which is obvious.
To heat up at 2,500 rpm & cool off at 2500 rpm means there is a open & closing of exhaust gases into the cooling water.

OR

The cooling system does not increase water coolant flow fast enough. Did you do a water pump rubber impellor replacement with the thermostat ? Evinrudes have a jerkoff impellor seal plate gasket. 2 ways it goes in. YUPP. right & wrong. Your previous guys DIY ??.....You can not believe ANYTHING is right on any area. Did they seal all exhaust surfaces ?
Acrack in the head or block ??

......Edit & a hope not.

If the pump impellor is broken off or parts missing ? You have a BASTARDLY job finding the pieces pushed up the coolant passages........

Put a long metal straight edge across the head chambers at different places. Do the same with both cylinder block surfaces. I do those checks at dark with a flashlight.

Aluminum CAN " ROT " . It starts to go softer with enough high heat cycles. In the metals properties book.
My 52 ford flathed ...Aluminum carburator base lost it. After the 3rd resurfacing, I bought new.

Useually I can see where the exhaust leak is. VERY CLEAN area with a color that does not look like the rest of the water cooled areas. It really jumps out to be seen.

Idea. In neutral. Run the engine up & watch the underwater exhaust for steam trail..............you are out of the water.:facepalm:

Old brain loses it.

Keep searching for a DIFFERENT colored area due to exhaust heat or steam cleaning. You can find the SPOT OR SPOTS .

 

[cyclops2]

Re: 88 mercury black max 200 cylinder wall help

Forgot to ask you about the spark plugs appearences. You have to number them as you take them out. To find where a bad plug came from. Pull them & shoot us some pictures. A darker one or a lighter one is a suspect cylinder.

my brain is hurting.

Hang in there. It will show up.

 

[Faztbullet]

Re: 88 mercury black max 200 cylinder wall help

does the spheircal "hemi" portion of the head also have chrome or some kind of lining on them or is that just bare aluminum? becuase theres actully a few very very small pin holes there too

It just aluminum casting imperfection and will not cause any problems...

hats your opinon on the pin holes the definitly did not corroded from the water jacket side into the cylinder. so how did they get there?

They(holes) are no problem and were there when block was made...

how do you think they are the cause of my overheat if they dont enter the water jackets?

They are not causing any problems....how are you determining its running hot ? Are you looking at a temp guage or alarm sounding??? Make sure you installed the correct t-stats as it has to be the inverted flow style. Also check the divider plate and the cylinder feed passage as cooing water comes thru it first before it hits the cylinders or heads....

 

[cjlallo]

Re: 88 mercury black max 200 cylinder wall help

I determined it was running hot by the gauge and an infared thermometer. The thermostats water pump and popet were installed by a mercury dealer. There the ones that assumed the cooling passages were clogged and thats why I pulled the heads off. I also tried runing it without t stats with no difference. Temp was fine below aprox 2500 once it got hot I just back of and it droped back to normal pretty quick.

 

[cjlallo]

Re: 88 mercury black max 200 cylinder wall help

The holes from the divider plate section around tge cylinders are all clear but I plan to clean everything really well before reassembly. I ned to find new gaskets for the divider plate still and the ones on the backs of the head. Any suggestions?

 

[cjlallo]

Re: 88 mercury black max 200 cylinder wall help

???

 

[cjlallo]

Re: 88 mercury black max 200 cylinder wall help

Hey faztbullet you've been a huge help so far dont fail me now I could stol really use your help and knowledge thanks