Question for all you engine guru's out there. 3.0L head Question.

ddwood55 · Jun 10, 2004

I sold this head on ebay. The person I sold it to wanted a refund because he said it was a 2.5L head instead of a 3.0L head. He said my head had smaller valves and a smaller combustion chamber than the head off his engine. Here's what I found stamped on the head GM 2777770 and Hecho en Mexico (which I figure means made in Mexico). The serial number off the engine is OD444775 model number is MCM 3.0 Litre. I'm going to try and post pictures I hope it works. But I'd like to know exactly what head I have. And about what I can expect to get out of it.

Thanks, Delos

ddwood55 · Jun 10, 2004

Re: Question for all you engine guru's out there. 3.0L head Question.

Originally posted by DWood: [QB] I sold this head on ebay. The person I sold it to wanted a refund because he said it was a 2.5L head instead of a 3.0L head. He said my head had smaller valves and a smaller combustion chamber than the head off his engine. Here's what I found stamped on the head GM 2777770 and Hecho en Mexico (which I figure means made in Mexico). The serial number off the engine is OD444775 model number is MCM 3.0 Litre. I'm going to try and post pictures I hope it works. But I'd like to know exactly what head I have. And about what I can expect to get out of it. 

 

 

 

 Thanks

ddwood55 · Jun 11, 2004

Re: Question for all you engine guru's out there. 3.0L head Question.

Help me out on this. I need to get this head sold so I can buy the parts to finish my Mustang GT engine. I really don't want to relist it untill I know for sure what head this is.

TwoBallScrewBall · Jun 11, 2004

Re: Question for all you engine guru's out there. 3.0L head Question.

I can tell you it does not look like a 3.0 head. The head on my 1988 and 2002 3.0's both had four separated intake ports from what I remember, where yours has 2 large combined ports. I could be wrong, but I do have a definite 3.0L head in my garage I can take a few pics of later tonight and post here if you need me to.

ddwood55 · Jun 11, 2004

Re: Question for all you engine guru's out there. 3.0L head Question.

That's weird. Unless someone changed heads on that engine at one time or another. I know the new engine I purchased my intake bolted right up to and worked fine. Runs great and the water getting into the oil problem is fixed. I really didn't pay any attention to the ports on the new engine or intake for that matter. I didn't have any reason to think the head had ever been changed on the original engine. And the new engine was complete except for the manifold. Sure would like to find out for sure what head this is. Thanks, Delos

metwrench · Jun 11, 2004

Re: Question for all you engine guru's out there. 3.0L head Question.

I also dont feel this looks Like A 3.0 gm. I dont think it changes much for marine use, I work as an Auto Tech and it doesnt resemble a car 3.0 Good luck

ddwood55 · Jun 11, 2004

Re: Question for all you engine guru's out there. 3.0L head Question.

Well Phooey! So if it isn't a 3.0 head what is it? It is a GM head and that's all I know for sure.

affa · Jun 11, 2004

Re: Question for all you engine guru's out there. 3.0L head Question.

It looks like a early 80 mod Affa

rodbolt · Jun 12, 2004

Re: Question for all you engine guru's out there. 3.0L head Question.

hello some of the heads interchanged. there were at least 4 intake port combinations used on the 120/140-2.5/3.0 engines. by the looks of that rusty beast you should send it off for magnafluxing. looks like water was in it sometime. most machine shops have a manual that will give information about the casting numbers. GM has had those heads made in mexico since the late 80's or early ninties. the 3.0 merc engine shares no parts with any modern 3.0 made. the auto version has been out of production for some 30 years or so. good luck and keep posting

ddwood55 · Jun 12, 2004

Re: Question for all you engine guru's out there. 3.0L head Question.

Originally posted by rodbolt: hello some of the heads interchanged. there were at least 4 intake port combinations used on the 120/140-2.5/3.0 engines. by the looks of that rusty beast you should send it off for magnafluxing. looks like water was in it sometime. most machine shops have a manual that will give information about the casting numbers. GM has had those heads made in mexico since the late 80's or early ninties. the 3.0 merc engine shares no parts with any modern 3.0 made. the auto version has been out of production for some 30 years or so. good luck and keep posting

I've already had it manifluxed. The rust you are seeing is just surface rust that has formed since the head has been off the boat. It's been setting on my carport and I just the high humidity in Arkansas is getting to it. So it could be a 3.0L head only an earlier model. I wonder what it's doing on a 90 model 3.0L engine. It was in a 1991 Larson. The serial number shows (at least that's what a mercruiser dealer told me where I bought my parts) that the engine is a 1990 model. When I bought the boat I knew it had problems. The person I bought it from said he was in the Arkansas River and got something up the water intake and got it extremely hot, it quit running on him and had water in the oil. When I got the boat home I pulled the lower unit and he had burnt up just about everything. The water impeller was in a bunch of pieces. I purchased everything new, impeller, housing, all new exhaust hoses and at that time I bought a headgasket and installed it. When I got it put back together I hooked it up to a water hose and ran it probably for 30 minutes or so. Everything seemed to be fine. But when I took it to the lake water was still getting in the oil. that's when I had the Head and Intake/Exhaust manifold maniflux. Everything showed to be good. Bought some new gaskets put it back together and still water in the oil. Couple a months ago I bought a complete long block, used my old intake/exhaust manifold and have had no problems since. I contacted the guy that I bought the boat from and he said as far as he knows the head had never been changed out. So if it's an 80's model head what was it doing on a 90's model engine? This is really a pain. I emailed the person I bought the new engine from, sent him the pictures and casting numbers maybe he can shed some light on to what head this is. Thanks,

Mercathode · Jun 12, 2004

Re: Question for all you engine guru's out there. 3.0L head Question.

Dwood Mercury had the 2.5 liter 120 hp and the 3.0 Liter 140. Then sometime around the late 80 and early ninties they dropped the 2.5 and after gave the 140 and new prop rated hp of I think around 120. Then added a new head and bigger carb to the 3.0liter and called it a 135. So you actually had to different rated 3.0 engines. I just wonder if yours is not the old style 125 3.0 and the guy that bought your head has the higher horse engine?????

ddwood55 · Jun 16, 2004

Re: Question for all you engine guru's out there. 3.0L head Question.

Ok, I had the machine shop that does all the work for the Mercruiser dealer in Hot Springs, AR run the casting number off the head. Here's what I found out. Casting number GM 2777770 Mercruiser 3.0, 181ci, used from 1974 - 1993. So from that I guess I can assume it is a 3.0 head. But it didn't tell me what horsepower engines it came on, etc... But from what everyone here and the person that originally bought the head when I had it on ebay there must be more than one head used on the 3.0's. Thanks,

Question for all you engine guru's out there. 3.0L head Question.

Cadet

Cadet

Cadet

Lieutenant Commander

Cadet

Petty Officer 3rd Class

Cadet

Petty Officer 2nd Class

Supreme Mariner

Cadet

Petty Officer 1st Class

Cadet