Logo
FULL SITE MENU

1988 Mercruiser 57L thunderbolt timing

P

paul59

New member
"I have owned a 1988 Boat with

"I have owned a 1988 Boat with a Mercruiser 350, 260hp for the last 18 years. The boat has been garage kept and is in great shape. It seems to run well except for it wanting to die when shifted from gear to neutral. The engine also at times will run on once the key is turned off.

I would like to time the boat. I have been told that the Thunderbolt IV might need to be disabled in order to time it properly. One mechanic suggested it should have a purple wire with a white stripe coming off the ignition system. I do not believe this one has that wire to ground.

How can I find out the proper procedure for timing this boat? Any other ideas on what might be causing the problem?

Thanks"
 
"the 88 TB shouldnt use a shun

"the 88 TB shouldnt use a shunt so just time it normally.
stalling while coming in/out of gear is a bad shift cable usually.
run-On might be engine temp, too fast a idle rpm,
high carbon build up on the piston, not allowing the engine to cool after a hard run before shutting it down."
 
Bt Doctur thanks for the infor

Bt Doctur thanks for the information.I did set the idle higher to try to help keep it from dying. I will rest it to the proper RPM.

Please tell me more about the shifter cable. Would it be bad or just in need of adjustment? How can I check it to see if it is bad?

Thanks
 
"[b]"Please tell me more a

""Please tell me more about the shifter cable. Would it be bad or just in need of adjustment? How can I check it to see if it is bad?"

Ayuh,....

When the Lower Shift Cable gets old,+ goes Bad, the added resistence causes the motor to stall....
If you haven't changed it in 18 years,...
It's Waaaaay Over Due.....

Btw,...
With the T-Bolt IV, that you have,... Just hook up the timing light, point, shoot,+ set....
Nothing to disable...


There's a thread titled "Ayuh, the backdoor is again Open",...
The Manual for your motor,+ drive can be found there...."
 
Bondo I appreciate the advise

Bondo I appreciate the advise and it sounds like this is the way I will address my problem. I appreciate the input and the expertise I have been offered.
 
"I would not recommend re-timi

"I would not recommend re-timing the motor. Just check it!!!!

With the IV electronic ignition the initail timing should never change!!!!!!

If you have adjusted it for what ever reason then by all means reset it.

If you are not familiar with the shift cables especially the short cable and do not feel comfortable doing this, ( it is not easy for a novice) then have someone who understands what and how to do it. It will save you several days of agrivation when the experienced person will have it don in a few hours. Plus you will need one special tool to install the new cable and I can guarentee you do not have it!!"
 
"Thanks for the advice Kghost.

"Thanks for the advice Kghost. I am pretty good on mechanical items.I am interested in knowing the tool that I will need that I will not have in my collection. If you have any advice to make this go easier for me, I would appreciate hearing it."
 
The brass fitting on the end o

The brass fitting on the end of the cable has a 1/4 npt thread. It is a 9/16 hex and the plastic tube of the cable stick out to far to use a deep dish socket.

Get a 3/8 extension the one that is about 2 1/2 inches long or so and drill it out straight thru with at least a 1/4 inch dia drill bit. This is what I have. Otherwise you need to purchase the "special" merc tool.
 
"Once again, Thanks for the ad

"Once again, Thanks for the advice. I will try it this weekend. I read over the procedure last night and it doesn't seem to be too scary.

Many thanks to all who gave advice. I bought the lower shifter cable kit yesterday. Hopefully this will solve the stalling issue.

Thanks!"
 
I replaced the cable over the

I replaced the cable over the weekend. I decided to tack weld two deep well sockets together to get the depth needed to loosen the 9/16" end of the cable. The sockets where easily separated after the pair.

The repair worked well in the driveway yesterday and would expect the same on the lake soon.

Thanks for the advice.
 
"I have a 1993 350 Magnum with

"I have a 1993 350 Magnum with the TB4 ignition and recently had the following problems:
1: run on after turning the motor off
2: occasional backfire on WOT acceleration
3: top speed RPM down about 300 RPM
4: sluggish acceleration

I took a timing light to the motor this weekend and wouldn't you know - what was supposed to be 8BTDC was actually 4ATDC. How this happened I don't know - we've never had the timing adjusted. Anyway I put it back to 8BTDC and all the problems went away. As someone else said it was very easy - while the TB5 systems require a white/purple lead to be gounded to defeat the mechanical advance I just adjusted the TB4 it as it was, and did the timing at below 700 RPM."
 
"[b]Tune it. New coil, new dis

"Tune it. New coil, new distributor sensors, new plugs, wires, set the timming dead on, check your grounds. It is a weak spark issue.

I have found that a weak spark will cause the engine to die when going in and out of idle. This works for EFI and carbureted engines."
 
Back
Top