IL6 engine ID?

Hi folk,<br />I got what i wanted for Christmas. sparkplugs for my old toy. seems that i don't know what engine i have to specify the right plugs though. i've got some histoy (paper work, reciepts) on this boat as it came from my Dad(deceased in aug. 02). The motor was R&R in june of 98 by a mercrusier shop in MN, recipt says it's a rebuilt shortblock. hum, that's all it says other than $1044. anyways, went out to get my serial number off the block to be sure i got right plugs. can't find it. clymer book says it's above the starter on the starboard side, on a tag. i got no tag that i can see. i also have no sticker on my valve cover, just the left over glue. heres what is stamped best i can see on the block. these are all raised letters or numbers. about under the #3 cylinder, on side of block are the numbers 473483, under that number is GM, then under that is the number 92. about under the #4 cylinder is the numer E49. about under the #5 cyl. is CON2. and further to the rear by CON2 is the clock pic. set at number 3. one other number that i can spot is right behind the distributer. on a machined flat spot. these numbers are stamped into the block, not raised. these numbers are F0518TAJ, under that on the same flat is the number 95934. anybody know what motor i've got here?

Re: IL6 engine ID?

been looking on line and am starting to think i have a car or truck engine. assumming that because of the number on boss behind distributor, and no tag rivoted to block by starter. so far think F=flint, 05=may, 18=day. TAJ= engine suffex code, don't know what that code is yet. clock appears to have relivance to shift and time of casting at the mfg. still don't know what plugs i need though. any other info that i can supply to figure out what plugs to use?

Re: IL6 engine ID?

I don't understand the Problem........<br />You have a 250 CID, 165 HP IL6 mercrusier........<br />Pull 1 of the plugs in it Now,+ Read the #s.......<br /><br />Older Heads used a large based plug that took a 13/16ths socket......<br />Newer heads use the same MR43T plugs that All the newer Chevies use.......

Re: IL6 engine ID?

there apperently are 2 different plug application for this motor, depending on what the sereial number is. per clymers manual, which is all i got. 165 model, 250, serial number up to 2771483, use plug AC-CR44N. 165 model, 250, serial number 2771484-up, use plug AC-MR43T. i don't know what my serial number is, my serial number don't appear to be located where it is supposed to be, per the manual again. my numbers also don't seem to fall in the proper range of serial numbers.

Re: IL6 engine ID?

Older Heads used a large based plug(AC-CR44N) that took a 13/16ths socket......<br />Newer heads use the same MR43T plugs that All the newer Chevies use.......

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Read this Again........<br /><br />Your Block has been Replaced....... <br />The #s you're finding are NOT going to Help you......<br />For that matter, It Doesn't Matter........<br /><br />The differences are the HEAD.....<br />I've Told you the difference between the 2.....<br /><br />Pull a plug wire,<br />Try to slip a 5/8s" socket onto the plug....<br />Does it Fit ???? If YES, you need the AC-MR43T plugs......<br />If the plugs need a 13/16ths" socket, Then you need the AC-CR44N plugs..........<br /><br />There are Only 2 Choices..........<br />1 is an 18mm based plug......<br />The other is a 14mm based plug.........<br /><br />Again, Forget about the serial#.....<br />Pull a plug out of the head,+ replace them with the Same # that's in it NOW........

Re: IL6 engine ID?

Z . Bondo is setting you right.Use the SAME plug that's in the motor now.It has worked all these years.GO with it.It hasn't hurt a thing.<br /><br />DHP

Re: IL6 engine ID?

thankyou peoples, i guess i made a mistake when i got the boat. didn't read the serial number correct, and replace the plugs myself. with MR43T. they seemed short compared to what was there. i don't have what was there to start with. though i do have the reciept as to what dad was haveing installed. champion RV15YC4. which don't cross best i can tell to either, least it comes up with a different ngk number. guess at this point i will go with the CR44N, if it will bolt on, certainly the head won't accept the 13/16 socket down into the head. perhaps the drive part of the plug is above the head. (or is this what yer refering to bondo when ya say older head used a large base plug and took the 13/16 socket)guess i will see next spring when i get to replaceing them. didn't do that today. now i wonder why the merc dealer that R&Red the motor used the RV15YC4's. on that idea as stated above, that worked for years, why change. except that it's not what the clymer book calls for. i agree, only 2 choices, and don't look like the RV15YC4 is one of the options. thanks

Re: IL6 engine ID?

ziggy.. as well as 18mm and 14mm thread sizes (width) plugs also come in two different thread lengths 1/2 and 3/4 inch.. u cant really get the width mixed up but u certainly can the length.. fitting a long reach plug in where a standard one should go can do damage to the piston or valves.. make sure u dont do it.. then u have the taper seat plug and the one with a washer.. u can get these mixed up if u dont know any better.. if u do the plug wont seal properly..<br /><br />folks dont always use the manual recommended plugs.. sometimes thru error sometimes thru choice.. i dont use the plugs the manual recommends in my boat.. cos i spent a lot of time at no-wake just above idle speeds with a very cool running engine.. i use a hotter heat range plug than the one the manual says.. i also use a projected nose plug as opposed to a standard nose plug simply cos everything i read tells me they work better and if there is room for em use em.. course that does make me wonder why the manual tells me otherwise.. he he <br /><br />praps u should educate yourself.. do a google search for spark plug codes or simply just sparkplugs and find out what those numbers actually mean and why they are there sometime over the winter.. they aint just simple part number codes.. they do give u usefull (and otherwise hidden) information about the plug.. <br /><br />trog100

Re: IL6 engine ID?

trog, educating myself is what i was hopeing to accomplish here. educating myself about which were the right plugs for the engine that i've got. i'm understanding about a long plug vs the short one. the rv15yc4's were longer than the mr43t. so didn't think i'd do physical damage to the engine, and it seemed to run fine after replaceing the rv15yc4's with mr43t's. i just thought i might start with the oem plug since there does seem to be a diffence in length at the very least. i am confused as to what plug to use since it appears that i don't have a oem engine(which i understand to be irrelevant) and it didn't have what i thought to be oem plugs in it when i got it. so i was trying to find that info out. i don't want to over think this. but want to be right. maybe i will go out and swap a plug tomorrow. bondo says its as easy as one will work, and one won't, and i got one of each. the 5/8 socket on the mr43t that's in it now works dandy per that method. maybe i got what i need in it now and just ain't ontoit. trying to get that way though .... thanks for the help all..

Re: IL6 engine ID?

The Champion plugs are longer than other plugs and has nothing to do with how they work. The thread length and electrode length, heat range etc. are what you need to look for. Use the MR43T plugs and get rid of those #&$^% Champion plugs altogether. They cause more problems than they cure.

Re: IL6 engine ID?

Use the MR43T plugs and get rid of those #&$^% Champion plugs altogether. They cause more problems than they cure.<br />

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Absolutely......... Couldn't Agree More..........

Re: IL6 engine ID?

well, i was all set to think that the MR43T was the way to go. but no, i had to go see my merc dealer here. bummer. he thinks(no make that says) that i should be using the champion RV15YC4. worse yet he showed me his champion ref. book with that being the proper number. as i've read post here i've come to respect a lot of opinions here. so i've got a delimma, dhp you and the merc dealer here(and the merc dealer that did the rebuild in MN used them from square one) say use the champions, bondo and donS say the MR43T. the plugs are pretty close to the same. but ya can see the diff. quite a difference actually. guess more to the point is donS (and bondo concured), ya say they cause more problems than they cure. what are they tryin to cure, and what problems are the creating? the RV15YC4's. guess i'm gonna have to have a real merc service manaul soon, not the clymer's that i got. would like to see what that says as to oem plugs. guess with everyone's help i've also decided that my orig. serial number probalby fell above 2771484, thanks. boating sure is fun.....

Re: IL6 engine ID?

ziggystardust,<br /><br />Take Bondo's advice. The plugs are either the big thread ones or the small thread ones. Not a big deal. I would go Delco over Champion.<br /><br />That's NOT a sophisticated engine. It would probably run with hot coals stuck into the plug holes.

Re: IL6 engine ID?

ziggy.. spark plugs discussions are like oil discussions.. they can go on for ever with narry a positive conclusion..<br /><br />there are about four main makers.. Champion.. NGK.. AC.. Bosch and a few others.. to confuse u they all use different codes to denote which plug is which..<br /><br />they all make a plug for almost every application.. they all sell millions of plugs and they all have millions of happy users.. assuming u use vaguely the right type it really dont matter what make u use..<br /><br />i dont believe u will go far wrong with following dons or bondos advice..in fact i know u wont.. but they do kinda talk in absolutes.. the problem being of course other experts also talk in absolutes.. only different absolutes..<br /><br />what the hell is a novice sposed to do when he asks four different experts and gets four different answers except get kinda puzzled..<br /><br />this is not the best place to learn about sparkplugs.. all u will get on here is "opinion".. the internet is awash with sparkplug sites and all u need to know about em is readily available.. course it wont provide an "instant" answer.. it does take some time and effort to learn anything thats worth knowing..<br /><br />otherwise remain forever puzzled about why four different experts are quite likely to give u four different answers about most things.. he he<br /><br />measure the thread depth on your cylinderhead to make sure u have the correct reach plug then go from there.. the end of the plug (not the electrode) should reach the end of the thread in the head.. also make sure that the surface the plug mates up with is either flat to take a washered plug or tapered to take a tapered seat plug.. and if GM came up with as many variations on a theme with the cylinderhead on your engine as they did the 3.litre.. u could be anywhere..<br /><br />the other thing to note is that these old cast-iron GM boat engines are just simple cooking engines.. they dont make any special demands on sparkplugs other than the fact that they fit properly.. there is also plenty of room in the combustion chamber so slight variations in plug length wont matter either.. they aint highly tuned racing specimens which can be very critical....<br /><br />personally i like NGK plugs... he he he <br /><br />trog100

Re: IL6 engine ID?

Well laughing boy (he he he) I change a lot of spark plugs every year. So do customers, and when they do their own work and put in Champions many of them start having problems after an hour. If I see a Champion plug in there I change it and usually that cures the problem. I also see the insides (the porcelen part you put the plug wire on) blow out of them. I have NEVER seen this happen on any other plugs. I would trust a 10 year old NGK, AC, or Bosch before a new Champion. My guess is anyone that works on lots of different boats sees the same thing from what I hear. But you are right......the internet is full of opinions.<br />Using the correct plug also prevents those unsightly holes in your pistons when you are changing plugs without knowing what you are doing.<br />As a backyard hack, you probably don't have to back up your ideas by paying the repair bills if your wrong........I do.

Re: IL6 engine ID?

DonS wrote:<br /><br />

As a backyard hack, you probably don't have to back up your ideas by paying the repair bills if your wrong........I do.<br />

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I rest my case, go with the AC/Delco plugs that fit your application.

Re: IL6 engine ID?

course the other difference tween the backyard guy and the professional one "very serious none laffing boy" is that someone who is being paid to do work and who doesnt want it to come back on him.. also is spending someone elses money.. and has every incentive in the world to replace every thing is sight just in case.. he also aquires a reputaion for doing a "good" job..<br /><br />however he has no incentive at all for attempting a task that has only has a fifty/fifty chance of working but if it did work might well save his customer a fortune..<br /><br />i am a backyard mechanic thow at times in my life i have been a paid one so i know exactly where u are coming from..<br /><br />okay so u dont like champion plugs.. your "opinion" is based on experience.. the fact that champion is probably the worlds best known and best selling plug does tend to bring your opinion into question thow.. it might not be the "best" plug out there but no way can it be as bad as u suggest.. else i dont think they would sell quite as many as they do and champion would spend half their life fighting litigation cases..<br /><br />as for blowing holes in pistons and stuff.. u cant seem to grasp that the main gist of my posts was to prevent such happening by suggesting that folks really do find out how sparkplugs work..<br /><br />we do really sit on opposite sides of the fence don.. i try and make folks think.. u try and bludgeon em into blindly doing as they are told with fear of dire consequence if they dont..<br /><br />"Why is there never enough time to do it right the first time, but always enough time to do it again?"<br /><br />your sign off says it all don.. just bear in mind that money as well as time enters into the equation for most folks as well..<br /><br />take my "backyard" status for example.. i have lots of time but very little money.. i can afford to waste my time but i cant afford to waste my money.. to u don time is 75 dollars an hour so u cant aford to waste it.. it would be better for u to save time and fit a new part.. for me it would be better to spend some of my cheap time on trying to make the old part work even if it dosnt last another ten years and in a couple of years i have to do it again..<br /><br />stangely enough don.. i have a close friend who is very like u.. he is a "proffessional" and buys "last a lifetime" very expensive tools.. i cos of my "occasional use" status buy lots of cheap chinese ones.. he gets pissed off cos i have more tools than he does and even thow he dont like it on the odd occasion even borrows one of my "cheap chinese" .. i have two (cheap) old cars and a boat.. he has one new car and cant afford a boat so he says.. he has far more money than i have (in truth he is loaded) but less time and never stops kidding me that i must be "rich" cos i have two cars and a boat.. he he<br /><br />there is no "correct" way of doing anything don.. there are cheap ways that stand some chance of working.. there are not so cheap ways that stand more chance of working.. and there are very expensive ways that stand every chance of working.. and thats only on the money side of things.. there can be quick ways that stand some chance of working not so quick ways that stand more chance of working and very time consuming ways that stand every chance of working..<br /><br />and then of course we have that often quoted "correct" way of doing things.. the way that takes the most time and the most money.. my only problem here is that i never have been able to afford the last option.. so even thow it might be the "correct" way for some.. it certainly aint the correct way for me..<br /><br /><br />and above all else if i bugger something up i only have myself to answer to.. i do hate it when i waste money thow.. he he <br /><br />horses for courses don.. u takes your choice and u pays your price..<br /><br />please try and tolerate me.. i do u.. he he<br /><br />trog100

Re: IL6 engine ID?

Don it sadden me to see people attack a person who gives many hrs. of his time and expertice on a site like this, if they knew any thing they would know every profession mechanic does not agree on certain products, you try to give straight up professional answers to people. With the amount of padding that goes on here, its great to hear from someone with good answers --Bob

Re: IL6 engine ID?

hi, thanks for all the great responses. i had a good day boating today( considering it's winter that is). am gonna use ngk, BR6FS. the cross ref. of MR43T. this is after taking the boat to the mercruser dealer today. no, didn't take it in to confirm the plugs, but surely did talk about that. in the end they agreed that it was proper to use the BR6FS, the cross of MR43T. think we all had it pretty well narrowed down here. useing ngk cause that's what the dealer had on hand. ironicly, it seems that most likely what bondo said from square one would have been the confermation for the proper plug. socket size . i'm kinda agreein with laddiesservice. it saddens me, the attacts. aint there enough hate & discontent in the world today. we don't need more. were all here just to help ourselves with our passions, boats. we all have opinons here. the question wasnt' really champions vs ac or ngk or whatever. it was about the fact that i got no serial number on my engine to comfirm what is the proper plug to use. i can understand donS's concern about the porciln being very exposed on RV15YC4's. i wondered about that myself. the rv15yc4's and the mr43t's are very simialer, except that the center electrode is flush with the bottom of the plug on the mr43t's, and protrudes maybe a 1/4" past flush on the rv15yc4's. i just wanted to use the correct plug. if i need to adj. heat range i will go read about modifying that to suit what i need. will probalby ask more questions too. the way i see it is that if i get 10 different ideas, i can weed thru them, agree or disagree with what is being proposed and then hopefully make a educated disission about the question that's been asked. think this is why i like these forums, the more info ya get, the better decission i can make. <br />just as a side note, the boat was at the dealer today to have the lower unit removed and inspected. better late than never. got a clean bill of health from the mercrusier dealer...and now i know what plug i'm gonna use. . have a prosperous and Happy New Years to all.