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Results 1 to 30 of 37
  1. #1
    Join Date
    Dec 2009
    Location
    Lafayette, LA,
    Posts
    26

    Default I'm trying to identify wha

    I'm trying to identify what ignition system I have on my motors. Boat has twin 4.3L V6's with Alpha drives. One motor is a 1998. The other is a 2004. They are not fuel injected and have carburetors. The 1998 has an ignition module bolted on the exhaust manifold. The newer motor only has a small module mounted on the distributor. I think the timing is not right and know there is special timing procedures for the thunderbolt ignition systems. Any help would be greatly appreciated. Thanks

    One other quick question. The 1998 motor is a LX. The 2004 motor is a LH. What does this mean. Thanks again.

  2. #2
    Join Date
    Jun 2006
    Location
    Spotswood, NJ, USA
    Posts
    2,734

    Default "This covers both systems [ur


  3. #3
    Join Date
    Dec 2009
    Location
    Lafayette, LA,
    Posts
    26

    Default Thanks. It looks like I have t

    Thanks. It looks like I have the Thunderbolt IV on the 2004 motor and the the TB V on the 1998 motor. Now I just need to get both motors to turn past 3600 rpm. I have a feeling there is more than one problem going on. Incorrect timing and fuel issues related to ethanol and old fiberglass tanks. Been working on these issues for a couple of years now. No luck with the mechanics I have used. Bummed out.

  4. #4
    Join Date
    Dec 2006
    Location
    Chaumont Bay, N.y., USA
    Posts
    4,230

    Default "[b]"Now I just need to ge

    ""Now I just need to get both motors to turn past 3600 rpm. I have a feeling there is more than one problem going on."

    Ayuh,... Give this a read...
    http://forums.iboats.com/showthread.php?t=295070"
    Any Grease is Better,... Than No grease at All....

  5. #5
    Join Date
    Dec 2009
    Location
    Lafayette, LA,
    Posts
    26

    Default "Yeah, this is super frustrati

    "Yeah, this is super frustrating. When the 2004 motor was installed, it was never right. Would only turn to 3800 rpm and would backfire alot. 1998 motor would run fine, turning up to 4300 rpm. Its been like that since 2004/2005. Boat lives at the camp in a sling. Would only run the boat for short cruises to keep engines running. I finally got a trailer for the boat and brought it to a mechanic in may of this year. They kept it for 11 weeks the first round. Didn't get it right. Then kept it 9 weeks and its still not right. Now both motors will only turn to 3600 rpm. Still think its the timing and carburetor and hoping its not the fuel. Cant find anyone good to work on mercruisers where I live. Very frustrating."

  6. #6
    Join Date
    Oct 2008
    Location
    Lakewood, NY USA
    Posts
    317

    Default "Will, Where do you live???

    "Will,

    Where do you live??? It is not on your profile nor on any of your posts?? That might help us out a lot!!Thanks"

  7. #7
    Join Date
    Dec 2009
    Location
    Lafayette, LA,
    Posts
    26

    Default "I live in Lafayette, Louisian

    "I live in Lafayette, Louisiana. Forgot to mention that we had a bran new carburetor installed on the 1998 motor while it was at the mechanic the first go round. This carb was purchased back in 2004 for the motor that blew but we never installed it. Just been sitting in a box in the garage. So, on the 1998 motor, I went from a good working motor prior to bringing it to mechanic, to a motor that only turns 3600 rpm with a new carb. I asked the service manager if he knew anything about the TB V special timing procedures and he seemed pretty clueless as to what I was talking about - didn't get word from actual mechanic if he knew about this. Was in the boat on Friday draining the exhaust manifolds and inspecting distributor on 2004 motor (TB IV ignition, I think) and noticed that the whole distributor/cap assembly could rotate with very little hand pressure. I'm no expert but this doesn't seem right."

  8. #8
    Join Date
    Jun 2006
    Location
    Spotswood, NJ, USA
    Posts
    2,734

    Default "That would throw the timing o

    "That would throw the timing off a bit, if anything use 2 hands to adjust.
    First , verify the spark plug firing order TWICE
    compression test, verify the throttle opening is all the way with the control box in full fwd.
    verify the gear ratio in the drive units,if the boat has never reached the WOT, you may have the wrong gear ratio in the drives."

  9. #9
    Join Date
    Mar 2008
    Location
    Manalapan, nj, usa
    Posts
    3,727

    Default "Great list, there is no bette

    "Great list, there is no better mechanic then the poster.

    Too bad your not in NJ or near the poster, he's on the west coast.

    Your going to have to go down the list, one at a time.

    You can rule the gas out if you run that motor on a external tank of fresh gas, and go back after you fix the problem and deal with the gas issue.

    Dirty bottom is self evident. Your on a trailer now.

    Dist problem could be fixed easy. With a hei unit.

    Motor should also be warm for the compression test, and heres links for a vacuum test, sometimes even more important to run one.

    http://www.users.bigpond.com/ergoff/vac1.htm

    http://www.secondchancegarage.com/public/186.cfm"

  10. #10
    Join Date
    Dec 2009
    Location
    Lafayette, LA,
    Posts
    26

    Default "Thanks for all the help guys.

    "Thanks for all the help guys. I'm feeling better about this situation and might try to time these motors myself. Just picked up a timing light and vacuum gauge today. I'm still not sure what ignition systems are on my boat. The 1998 motor only has an ignition control module mounted on the exhaust manifold. No sign of the knock sensor module anywhere. The 2004 motor has the ignition module? mounted on the side of the distributor. The electrical systems link posted by Bt Doctur is a big help. I'll post pictures of the systems when I can get some pictures. I still suspect that the old motor is TB V and the newer motor is TB IV or HEI.

    A little history on the boat. Its a 1971 25 Bertram Hardtop. It has always lived at the camp in the boat house, raised out of the water in a sling. No bottom issues. Its been repowered a couple of times, last being in 1998 with the twin 4.3L V6's with 4 barrel carbs and new alpha drives. In 2004 we blew the starboard motor and only replaced the motor keeping the existing outdrive and prop. Prior to blowing that motor (caused by leaking exhaust manifolds) the boat would run great with both motors turning up to about 4300 rpm. Both outdrives and props are the same. The only thing different now is the newer engine (2004) on port side and new carb on the old (1998) engine.

    I'm going to try and run these motors from external tanks. We'll see what happens. Any chance that I have bad knock sensors. How often do they fail. Thanks."

  11. #11
    Join Date
    Jul 2008
    Location
    Northboro, Ma, USA
    Posts
    3,502

    Default "Based on my memory(???

    "Based on my memory(???) if the timing ignition module is mounted on the manifold it is a model IV (4) also the wires comming from the distrinbutor sensor will be hanging out of the back of the dist housing or there will be two studs to mount the wires to,

    if you have a distributor with the ignition timing module mounted on it (a single module) not 2 piggy backed then you have a inbetween model IV and V. I remember there bieng v8 merc ignitions with the module mounted to the dist with NO knock sensore module just like the V6 in the pdf listed above. I could be wrong...........

    If you have piggy backed module set up then you have a model V. Your distributor cap MUST look like the ones in the pdf listed above!!!!
    If you have the knock sensor the sensor itself will be on the starter side of the engine and it will be installed at the block drain just forward of the starter.

    If you have the knock module and no sensor then you will be missing a 8-10 volt signal needed for the ignition module and without that signal the motor will stay in a "base timing" mode and willnot advance correctly. When the sensor detects a knock it takes the 8-10 volt signal and drops it down to 0 causing the timing module to retard the timing.

    Hope this helps to clarify some....."

  12. #12
    Join Date
    Mar 2008
    Location
    Manalapan, nj, usa
    Posts
    3,727

    Default "Just for discussion purposes,

    "Just for discussion purposes, maybe to have a buddy that might have a hei unit laying around.

    I am fortunate to have 5 friends all mechanically mined people with different " expertise ". We sorta pool our junk piles to see if we can fix whatever went wrong with equipment. If all else fails i call BT, and he rides over with his mint harley i think 72 just rebuilt the motor he says with that mismarked from the factory brand new back then cam gears.

    What i am trying to post is yanking the dist. and throwing in a " borrowed " hei unit.

    One wire in, one wire out.

    Takes out the sensors and all the other bull that can f up your motor.

    Might pay to yank it anyway the dist, look at the cam, is it worn? Could someone have used the wrong spring in the oil pump?

    All just speculation and discussion."

  13. #13
    Join Date
    Dec 2009
    Location
    Lafayette, LA,
    Posts
    26

    Default "Thanks for the replys. My 19

    "Thanks for the replys. My 1998 motor definitely has the ignition control module mounted on the exhaust manifold with no piggy backed knock sensor module. The 2004 motor has the ignition control module mounted on the distributor but doesn't have the knock sensor module piggy backed to it either. This one looks like the TB IV in the pdf link. If it is in fact an in between model, are there any special timing procedures.

    Unfortunately, I dont know anyone with mercruiser engines. I do have the old distributor and ignition control module that came out of the blown 1998 motor."

  14. #14
    Join Date
    Jul 2008
    Location
    Northboro, Ma, USA
    Posts
    3,502

    Default "If both are TB IV the there i

    "If both are TB IV the there is no specific timing proceedure. Just set initial timing to ~ 6-8 drgrees befor TDC.

    If you had a knock sensor/module then you would need to ground out a purple/white wire at the module ( hanging out in space by itself just for this purpose) to set timing controll to base level to allow initial timing to be set properly to ~ 6-8 BTC

    One more thing.....

    It is odd you have those ing modules at all.They must have just re-used when repowered. A 1998 or newer (carbed) would have the TB V or newer ignition if you had a complete repower.

    I just re read your posts completely and yes you have V6 (duhhhhhh.) so you have TB IV !!!

    there is no inbetween as shown in the pdf, it has the module ON the distributor....

    I thought you were running V8's. Either way we know what you have now......"

  15. #15
    Join Date
    Dec 2009
    Location
    Lafayette, LA,
    Posts
    26

    Default Great! It sounds like I have T

    Great! It sounds like I have TB IV ignitions on both motors. No special timing procedures required. Does this mean that I don't have knock sensors to worry about. I haven't been back to the boat to check the motors. This is also kinda bad news as I specifically asked the mechanics to time both motors. One would think they knew how to do this. Hopefully they just didn't get it right and my motors are still out of time. Still need to get more than 3600 rpm. Plus they accelerate terribly and sound like crap while running high rpm.

  16. #16
    Join Date
    Jul 2008
    Location
    Northboro, Ma, USA
    Posts
    3,502

    Default "Cant help you from here on th

    "Cant help you from here on the tune up from someone else.

    Also a distributor should not be able to turn by hand once set. the lock down bolt must still be loose. With these ignitions it IS a set it an forget it senerio............

    Also DOUBLE check your firing order, would not be the first or last time someone F' up that detail.

    Check your plugs and what they look like

    check the inside of the distributor for crap biuld up, moisture etc etc.

    One other thing,

    if both motors are not turning more than 3600 rpms then I would tend to think the problem may be from the same source....

    Try to get the one with the carb straightened out first as that may be the easiest to deal with.

    Twin motors are tuff to figure out sometimes.

    Also you may consider finding a new marina to do the work or have a special talk with the service personal working on your boat. If it aint fixed you shouldn't have to pay! That is my way of doing business.

    I win at repairs 95% of the time, but 5% I dont and when that has occurred I do not charge for my time only parts that the customer agreed to pay for. If it was my choice I ate the cost.

    Its called the cost of doing a good honest business. In my opinion anyway........"

  17. #17
    Join Date
    Dec 2009
    Location
    Lafayette, LA,
    Posts
    26

    Default "Kghost, Just wanted to say th

    "Kghost, Just wanted to say thanks for the good advice. I really like your line of thinking when it comes to repairs. If you were anywhere remotely close to where I live you would be getting my business. The boat dealer/service department I've been dealing with has been very fair with labor charges. The second go round with them this past summer (only 9 weeks in the shop as opposed to 11) they didn't charge me any labor. At this point I'm completely frustrated with them and dont think they really know what they are doing. I'm sure it doesn't help that I have a 39 year old boat with 11/5 year old power thats been poorly maintained over the years.
    Anyways, my plans going forward are to
    1) check and double check spark plug wiring
    2) inspect plugs, distributor cap and rotor
    3) check timing
    4) inspect throttle opening when controls are full forward
    5) run motors from external tanks
    After all that, if these motors still aren't going right then I'll have to find a different shop to take it to. Anyone know of a good shop near Lafayette, let me know. I'll keep ya'll posted."

  18. #18
    Join Date
    Jun 2006
    Location
    Spotswood, NJ, USA
    Posts
    2,734

    Default "you paying for gas? 1A)

    "you paying for gas?
    1A) compression test
    1) check and double check spark plug wiring
    1B) check each spark plug wire for a healthy spark to ground.
    2) inspect plugs, distributor cap and rotor
    3) check timing
    4) inspect throttle opening when controls are full forward
    5) run motors from external tanks
    "

  19. #19
    Join Date
    Dec 2009
    Location
    Lafayette, LA,
    Posts
    26

    Default Thanks for the help Bt Doctur.

    Thanks for the help Bt Doctur. New Jersey is a little far - make that - alot far from Louisiana. If only you were closer. I need to round up a compression checker. What should the numbers look like for these motors. I know for outboards they are around 110 to 130 psi and shouldn't vary more than 5 to 10%.

  20. #20
    Join Date
    Jul 2008
    Location
    Northboro, Ma, USA
    Posts
    3,502

    Default 140 -160 psi

    140 -160 psi

  21. #21
    Join Date
    Sep 2008
    Location
    Maryland - USA
    Posts
    5,598

    Default GM says within all within 15%

    GM says within all within 15% of the max and NONE under 100 psi - been that way since the last century

  22. #22
    Join Date
    Dec 2009
    Location
    Lafayette, LA,
    Posts
    26

    Default I checked all the spark plugs

    I checked all the spark plugs this weekend. They looked good as did the wires. I cleaned the contacts on the inside of the distributor cap. There was a little build up on each contact. Contact on the rotor looked good. I put everything back together and double checked wire placement. All good. I timed the motors and both were at 16 to 18 degrees at idle (engine warm). I adjusted both motors to 10 degrees. Today I ran a compression check on all cylinders. All came out at 155 to 165 psi after three compression cycles. How many compression cycles are you supposed to go through to get the right reading? Anyways I didn't get to run the boat so we'll see how that goes this week.

  23. #23
    Join Date
    Aug 2006
    Location
    SW Ohio, USA
    Posts
    10,328

    Default Try 650 RPMs at idle in gear a

    Try 650 RPMs at idle in gear and 8 degrees BTDC timing after your first run.
    Fix minor things (replace wear items for preventative maintenance.) that cause major problems before they break.

  24. #24
    Join Date
    Mar 2008
    Location
    Manalapan, nj, usa
    Posts
    3,727

    Default "Have someone drive while you

    "Have someone drive while you do the final adjustment you will hear when you hit the sweet spot. Don't be surprised if one motor is different then the other.

    Compression was checked on a warm motor with the throttle fully down? They look good anyway.

    Heres a link that will let you read the plugs after 5-10 hours running it.

    http://www.dansmc.com/Spark_Plugs/Sp...s_catalog.html"

  25. #25
    Join Date
    Dec 2009
    Location
    Lafayette, LA,
    Posts
    26

    Default "Chiefalen, At what rpm do yo

    "Chiefalen,
    At what rpm do you recommend adjusting while running.
    One thing I forgot to do when doing the compression check. I left the throttles in neutral. Choke was open though. Any Idea on the number of compression cycles you go through to get a good reading. Gauge reads 115, then 150, then 165 after three cycles. I ran a few cylinders 5 or 6 compression cycles and psi continued to increase. Maybe to 175 or a little higher.

    Guy. I'll give that a shot after first run."

  26. #26
    Join Date
    Jun 2008
    Location
    Island Heights, NJ,
    Posts
    1,658

    Default "When you mentioned ethanol/fi

    "When you mentioned ethanol/fiberglass tanks, I checked your profile and as I expected you have a Bert 25.

    Since this boat came with MERC 165 inline 6 cylinder, I question if the drive reduction ratio is correct... Inline 6s, I believe have higher torque than the V6s and may require a different ratio. The first hint on this is that the V6 MAX WOT is higher than the inline 6 RPMs as I recall... (I may be wrong..)

    My BIG question how did the V6s fit... When I owned a Bert25, I looked into the V6s and it appeared as if they would not fit side to side ???

    The other issue...ethanol and your tanks. I've seen posts on other forums ( Bertram related), that when the ethanol attacks the Bert gas tanks, the resin dissolves in the gas and get deposited inside the combustion chambers with drastic results.

    BTW...Congratulation on owning one of the best small boats ever made. I lost mine in a divorce in 1994 and to this day, every time I see one, I get a tringe."
    Capt Bob
    1969 23ft ChrisCraft Lancer
    Merc 5.7L 260HP/ Volvo 280
    1972 22ft Bristol
    Honda 7.5HP 4 stroke Long shaft

  27. #27
    Join Date
    Mar 2008
    Location
    Manalapan, nj, usa
    Posts
    3,727

    Default "Will: again on a WARM motor w

    "Will: again on a WARM motor with the throttle fully down.

    The gauge you have has the threads that screw into the plug hole?

    The book says that the compression should be between 10-15 psi of each other on the motor.

    If the motor was warm and throttle in fully down and they vary widely thaen i would suggest redoing the valves.

    Easy to do, and some do it such as myself WITH THE MOTOR RUNNING.

    Others do it with the gauge. Now if i remember correctly after running say 20-25 hours your supposed to redo the valves.

    Then leave them alone, what i would do is inspect all the studs, and springs, any pull out, brokin spring.

    You set the idle with a warm motor, in the water, in gear.

    600-650-700 no more.

    Finally i set the final, timing on the water actually by ear as my frine ddrives or i drive he sets it.

    You will know the sweet spot when you hear it , every motor is different.

    Finally , when the gauge stops moving could be 4-5 cycles, maybe more.

    Good luck, happy holidays."

  28. #28
    Join Date
    Dec 2009
    Location
    Lafayette, LA,
    Posts
    26

    Default "Robert, Thanks for the kind

    "Robert,
    Thanks for the kind words about the Bertram. Its a fine boat. Its actually my mom and uncle's boat. My grandfather bought it as a demo model back in '71 or '72. The boat is a 1971 hardtop version. Now, I'm the only one that uses the boat and thus get to do all the maintenance (I like working on the boat). My uncle foots the bill. Not a bad deal except for the fact that trying get my uncle to pay for some preventive maintenance is next to impossible. Example: we blew the starboard 1998 motor (in 2004) because of bad exhaust manifolds. Now the port motor has 11 year old manifolds and although they still work, probably need to be changed. Probably not gonna happen. Getting a new aluminium fuel tank, to prevent destroying both motors due to ethanol, not gonna happen either. I know all this is expensive but my uncle is fairly wealthy. If I were in a better financial position I would pay to have these things done. Maybe in a few years.

    The gear ratio in the outdrives is 2:1. The outdrives were new in 1998 with the new motors. When everything was working properly, we were getting 42 to 4300 rpm. A little on the low side but could be better with a little prop tweaking.

    The v6's in that boat really dont fit. It was a huge mistake to put them in. The transom openings had to be filled and then recut a little wider. The motor box had to be widened so there's only 10 inches or so on either side of the box. Due to the weight of the new iron, the scuppers are are underwater and covered by motor box. Needless to say, lots of modifications back there. 3.0L 4 bangers would have almost been a drop in replacement. Not that much of a loss in performance due to reduced weight. Still could of had a 25 to 30 mph cruise a 3000 rpm. What a bummer."

  29. #29
    Join Date
    Dec 2009
    Location
    Lafayette, LA,
    Posts
    26

    Default "Chiefalen, I'm going to

    "Chiefalen,
    I'm going to put the boat in the water today. We'll see how it runs. Thanks for the advice about the timing and compression checking. When I ran the compression check last weekend, all cylinders would get up to about 170 psi maybe more after 5 to 6 compression cycles. This was with warm motor but throttles in neutral position. I'll check again when I have time. The gauge I have is like you describe, threaded and screws into the plug hole. Thanks again -will"

  30. #30
    Join Date
    Mar 2008
    Location
    Manalapan, nj, usa
    Posts
    3,727

    Default "170 is excellent. If you boat

    "170 is excellent. If you boat is freshwater you will maybe never have to change out the mani's.

    I am not a great fan of shutters / flappers.

    Yours still there not fallen off and clogging the exhaust?

    Let us know how it runs.

    Could always do a vacuum test heres the links:

    http://www.secondchancegarage.com/public/186.cfm

    http://www.users.bigpond.com/ergoff/vac1.htm

    Both good sites, vacuum test reveals almost all."

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