1997 Merc 4.3 V6 LXGen+

[Proover]

Still no spark situation? First WAG on a t bolt system is ignition sensor in the distributor.

There is a thunderbolt troubleshooting guide in the stickies, top of forum page.

What is ignition sensor...in the distributor? Something under the cap? Or is it the Ignition Control Module on exterior of distributor?

 

[achris]

What is ignition sensor...in the distributor? Something under the cap? Or is it the Ignition Control Module on exterior of distributor?

Here you go... Have a read of this, it'll explain all the things you're asking about...

How Mercruiser Thunderbolt ignition systems work.

Mercruiser Thunderbolt ignition systems. Mercruiser introduced the Thunderbolt IV onto their engines in 1982, alongside the introduction of the 1-R drives. The TB-IV system was used until the introduction of TB-V mid-way through 1996. Thunderbolt V was an improvement on an already exceptionally...

forums.iboats.com

 

[Proover]

I've used wobble extensions and home bent wrenches as well...

Got it. Bolt was snug but slightly loose. Since motor ran good, & distributer twist was stiff & minimal, it's back where it was running good & I can forgo timing...for now. Thanks for the support.

More to come...I'm sure.

 

[Proover]

Here you go... Have a read of this, it'll explain all the things you're asking about...

How Mercruiser Thunderbolt ignition systems work.

Mercruiser Thunderbolt ignition systems. Mercruiser introduced the Thunderbolt IV onto their engines in 1982, alongside the introduction of the 1-R drives. The TB-IV system was used until the introduction of TB-V mid-way through 1996. Thunderbolt V was an improvement on an already exceptionally...

forums.iboats.com

Just ordered a new sensor. Every body part I can cross is crossed for luck. Arrives next week. Amazon.

 

[nola mike]

I can forgo timing...for now. Thanks for the support.

No you can't. You messed with the timing, it can't be done by ear. Over advanced can cause serious damage.

 

[Scott06]

No you can't. You messed with the timing, it can't be done by ear. Over advanced can cause serious damage.

Would second this. Marine engines under load have a much higher detonation potential than automotive applications, detonation that can eat your engine for lunch in a short time. Would suggest getting a timing light and setting it properly and verifying total advance

 

[Proover]

Well, as I said, the quarter inch counter clockwise turn was under significant resistance and it was physical stopped from any significant change. I put it back where it was when the boat ran fine. The resistance was enough to keep the distributer in place with engine running. So, as it's back exactly where it was, timing isn't critical. However, I have a vested & heightened interest in getting it to a shop for timing after & if I get it running again. I'm not going to remove a valve cover & buy special equipment to set the timing base.

I appreciate your feedback and, as I'm a novice (learning fast), & with economics the way they are, I can only hope I'm OK. So, wish me luck & I"ll let y'all know.

 

[Rick Stephens]

Really?

There is no mechanic on the planet would not tell you that setting the timing is essential. Go rent or borrow or buy a timing light and set it. How hard is that?

 

[Lou C]

Do you realize you are committing heresy in this audience of veteran shade tree mechanics, thou have sinned now do your penance and learn how to time your engine
or else, yea who have strayed from the direction of the good book (Merc Service Manual) shall suffer the slings and arrows of holed pistons and burned valves...repent...repent before it's too late! Yea who has desecreted the holy alter of the small block Chevrolet, created by the good Ed Cole, and GM engineering, in our year of 1955, repent, repent!



I've only been doing this since ah, about 1972 or so.....

 

[achris]

..., timing isn't critical.

Er, yes. Timing is EXTREMELY critical...

... I'm not going to remove a valve cover & buy special equipment to set the timing base.

Setting base mode is just a matter of grounding one wire. That's it! Who told you that you need to remove a valve cover?

I appreciate your feedback and, as I'm a novice (learning fast), & with economics the way they are, I can only hope I'm OK. So, wish me luck & I"ll let y'all know.

As you said, with economics the way they are... I would have thought you'd put more effort into get this right and making sure it doesn't cost you any more than necessary. Yet here you are buying cheap parts (that amazon sensor has a 50/50 chance of being DOA), allowing your engine to run without the timing being set properly (serious risk of eating a piston or 3), and then saying you'll farm out simple tasks to a professional mechanics.

My friend, you are a walking contradiction. It's your money and boat and you can do with it as you wish. Good luck to you, I'm out...

Chris....

 

[Proover]

Er, yes. Timing is EXTREMELY critical...

Setting base mode is just a matter of grounding one wire. That's it! Who told you that you need to remove a valve cover?

As you said, with economics the way they are... I would have thought you'd put more effort into get this right and making sure it doesn't cost you any more than necessary. Yet here you are buying cheap parts (that amazon sensor has a 50/50 chance of being DOA), allowing your engine to run without the timing being set properly (serious risk of eating a piston or 3), and then saying you'll farm out simple tasks to a professional mechanics.

My friend, you are a walking contradiction. It's your money and boat and you can do with it as you wish. Good luck to you, I'm out...

Chris....

Thanks for your critique...NOT. So freaking helpful you are.

 

[Proover]

Do you realize you are committing heresy in this audience of veteran shade tree mechanics, thou have sinned now do your penance and learn how to time your engine
or else, yea who have strayed from the direction of the good book (Merc Service Manual) shall suffer the slings and arrows of holed pistons and burned valves...repent...repent before it's too late! Yea who has desecreted the holy alter of the small block Chevrolet, created by the good Ed Cole, and GM engineering, in our year of 1955, repent, repent!





View attachment 362968


I've only been doing this since ah, about 1972 or so.....

LOL...So, I have time adjusted a few old school engines. No marine power plants. All old style point & rotor systems. And, it's been a while. What I've seen & found otherwise is timing this engine is quite a science. In the end, with this effort, I have not changed a thing other than the sensor. The distributor is in the same position it has always been in with a pretty good running engine. If all you have to do is hook up a timing light, then so be it. I can do that. But, if it involves partial engine disassembly and more, then it becomes a challenge. I should not have brought this forward.

Bashing me, like some seem to like to do, isn't useful or appreciated. But, I guess some see some level of value. Not me. Lou C? I do appreciate & understand your sermon...I deserve it as a novice amongst the pros. I don't deserve the demeaning & condescension. It's ugly.

 

[achris]

.. I don't deserve the demeaning & condescension.

What's condescending is a self-confessed novice (with no marine engine experience) telling a whole bunch of professional marine technicians that timing doesn't matter.

Now, if you're willing to put your pride back in your pocket we can talk you through the very simple process of timing the engine. The only tools you need are a simple timing light, a 9/16" spanner (for the distributor clamp screw) and a short length (6" is plenty) of wire (to ground one wire to put the ignition module into base mode). You might also need a white paint pen and a small tape measure. No partial engine disassembly required.

Chris.

 

[achris]

. So freaking helpful you are.

Well, reading back through this thread it does appear I have been quite helpful. Thank you.

 

[Proover]

What's condescending is a self-confessed novice (with no marine engine experience) telling a whole bunch of professional marine technicians that timing doesn't matter.

Now, if you're willing to put your pride back in your pocket we can talk you through the very simple process of timing the engine. The only tools you need are a simple timing light, a 9/16" spanner (for the distributor clamp screw) and a short length (6" is plenty) of wire (to ground one wire to put the ignition module into base mode). You might also need a white paint pen and a small tape measure. No partial engine disassembly required.

Chris.

I'll suck it up. What ya got?

 

[Lou C]

LOL...So, I have time adjusted a few old school engines. No marine power plants. All old style point & rotor systems. And, it's been a while. What I've seen & found otherwise is timing this engine is quite a science. In the end, with this effort, I have not changed a thing other than the sensor. The distributor is in the same position it has always been in with a pretty good running engine. If all you have to do is hook up a timing light, then so be it. I can do that. But, if it involves partial engine disassembly and more, then it becomes a challenge. I should not have brought this forward.

Bashing me, like some seem to like to do, isn't useful or appreciated. But, I guess some see some level of value. Not me. Lou C? I do appreciate & understand your sermon...I deserve it as a novice amongst the pros. I don't deserve the demeaning & condescension. It's ugly.

No one is bashing you it’s all meant in fun & we don’t want you to lose your engine. Sorry if it sounded like bashing it wasn’t meant that way….

 

[achris]

I'll suck it up. What ya got?

ok...

You're going to need to do some prep, nothing difficult, but it will make the job easier.. I think your engine has only a single line on the balancer and a cast notch on the timing cover. Those are TDC marks, not much help for setting the timing at 10° BTDC.

Three ways to solve that problem. Buy an 'advance timing light', that allows you to 'dial in' an advance and the light will flash that advance passed the actually spark, which means you line up the TDC marks and the timing is actually at the setting of the light. Unfortunately decent advance timing lights aren't cheap, so that option might be off the table.

Second option is to buy a thing called 'timing tape' and stick that on the balancer. Easy and cheap, but means getting to the shop to buy it...

Third option (my favourite) is to just make a mark (with a white paint pen or similar) on the balancer at 10°. So, where do you put the mark? Simple maths gives us the answer. If your balancer diameter is 6", then 10° is 0.52" away from the TDC line on the balancer. Just mark a line there and you have the right point... (If you'd like to see the math, just ask).

Now we will time the engine. Use the short length of wire to make a ground connection to a wire near the distributor. Find the purple/white wire, and connect it to ground. This tells the ignition module that you're setting the timing and it's not to mess around while you're doing it...

Connect the timing light to the spark plug wire #1 as near to the spark plug as practical (and away from any other lead) and check the timing marks. Should be a nice and solid position. If the timing marks are dancing around, the unit is not in base mode. Check the ground.
If the timing marks don't line up (and if you've replace the sensor, it's unlikely that will be), just loosen the clamp at the base of the distributor and very slightly rotate the distributor until the marks are lined up. Tighten the clamp bolt, check the timing again, then remove the ground wire and the timing light, and you're done...

Hope this helps,

Chris......

 

[Proover]

ok...

You're going to need to do some prep, nothing difficult, but it will make the job easier.. I think your engine has only a single line on the balancer and a cast notch on the timing cover. Those are TDC marks, not much help for setting the timing at 10° BTDC.

Three ways to solve that problem. Buy an 'advance timing light', that allows you to 'dial in' an advance and the light will flash that advance passed the actually spark, which means you line up the TDC marks and the timing is actually at the setting of the light. Unfortunately decent advance timing lights aren't cheap, so that option might be off the table.

Second option is to buy a thing called 'timing tape' and stick that on the balancer. Easy and cheap, but means getting to the shop to buy it...

Third option (my favourite) is to just make a mark (with a white paint pen or similar) on the balancer at 10°. So, where do you put the mark? Simple maths gives us the answer. If your balancer diameter is 6", then 10° is 0.52" away from the TDC line on the balancer. Just mark a line there and you have the right point... (If you'd like to see the math, just ask).

Now we will time the engine. Use the short length of wire to make a ground connection to a wire near the distributor. Find the purple/white wire, and connect it to ground. This tells the ignition module that you're setting the timing and it's not to mess around while you're doing it...

Connect the timing light to the spark plug wire #1 as near to the spark plug as practical (and away from any other lead) and check the timing marks. Should be a nice and solid position. If the timing marks are dancing around, the unit is not in base mode. Check the ground.
If the timing marks don't line up (and if you've replace the sensor, it's unlikely that will be), just loosen the clamp at the base of the distributor and very slightly rotate the distributor until the marks are lined up. Tighten the clamp bolt, check the timing again, then remove the ground wire and the timing light, and you're done...

Hope this helps,

Chris......

Sure does & thanks.

 

[achris]

Another poster just posted a picture of timing tape.. this gives you an idea of what it looks like and if you go the route of marking the balancer with a paint pen, roughly where to do it...

 

[Blorton]

Fwiw, I just checked Amazon, and the Innova 3555 model is going for around $50 and offers a manual advance dial. I just recently picked up their fancier version, but this one should suffice for your needs.