Mercruiser 5.7 Thunderbolt V issue

[steeler85048]

Hi all, I have been restoring a 1996 crownline 202 BR with a Chevy 5.7, thunderbolt V, serial 0F608827.

The previous owner water locked the engine and I decided to replace it with a chevy 5.7 vortec motor. I put a new water impeller in the outdrive I then re-installed the outdrive and installed all of the ingnition components.

I put a carbureted vortec intake on it with a marine quadrajet and all of the sensors and plugs mated up nicely. However, I have been having a problem trying to get it running. Initially when I first tried starting I noted that all of the plug wires from the distributor cap were on wrong. I then installed them correctly and it fired right off.

I hooked up the water muffs to the outdrive and ran it a little but the timing was off and it did not want to idle. I put a timing light on it and it was all over the place as far as timing goes. I tried to set the timing but got shocked when I tried to move the distributor. I then put all new plug wires on and it seemed to run smoother but I still did not get a good idle.

I then noticed that I had a gear oil leak from the water intake. I pulled the outdrive again and fixed a leaking seal carrier in the lower then pressure tested it and re-installed again.

I also noted that after looking thru the archives my battery was weak. I put two new batteries in as it is set up to run two and then tried to start it. This time I could not get it started. It acted as if it wanted to start but would backfire and diesel.

I checked the juice to the coil and noted that I had 12 volts...

My questions are as follows,
1) Could the ground with the second battery be worse?
2) Should I just junk the thunderbolt V ignition and go with the Delco Voyager set-up?
3) Suggestions on what to check tomorrow? I am going to check the tach to see if it's a problem and also will try to run on one battery, what else?

Thanks to everyone from a noob. Everything to this point has been pretty straight forward but electrical stuff is definitely not my forte...

Thanks in advance,
Philip

 

[Fun Times]

Re: Mercruiser 5.7 Thunderbolt V issue

I put a carbureted vortec intake on it with a marine quadrajet. However, I have been having a problem trying to get it running.

What carb model/part number did you get?.

I put a timing light on it and it was all over the place as far as timing goes. I tried to set the timing.

Sounds like maybe you didn't put the ignition system into base timing mode by connecting the purple and white wire to ground. http://www.boatfix.com/merc/Bullet/94/94_02.pdf

Try setting it to 10* BTDC.

 

[steeler85048]

Re: Mercruiser 5.7 Thunderbolt V issue

Fun Times,
thanks for the response and I have to say that after checking all of my connections (this am before work ) I noticed that I left a wire off of one of the batteries!!

I am guessing that this will somewhat fix the problem with starting. I will then work on the timeing after. Thank you so much for the info on timing. I will do that when I get home and hopefully get it on the water.
Here is what I did for a carb. I have a volvo penta carb I got that was a fresh rebuild. I had to modify the two barrely bracket to hold the throttle cable with the correct orientation...
View attachment 227399
Here is the old 2 barrel bracket with the old intake
View attachment 227400
Here is the new motor installed

And the boat in my garage

The old motor coming out

 

[Bt Doctur]

Re: Mercruiser 5.7 Thunderbolt V issue

Well ,if your going to get rid of a most likely perfect working condition T-V ,I`ll take it.
Dist base must be grounded using the pigtail wire. Initial timing can be guess-timated by bringing #1 to TDC Compression with timing mark at "0"
Drop in dist with rotor pointing to #1 position on the cap. Test start.
Shut motor off, put into base timing mode, set timing, shut motor off,remove jumper.

 

[steeler85048]

Re: Mercruiser 5.7 Thunderbolt V issue

Thank you Bt,
will try the timing with the purple/white wire grounded. i'm going to try and trouble shoot the system first before scrapping it. I just get frustrated with electrical stuff.

For some reason the pics of my carb didn't load so here they are again.

This pic shows the custom bracket I made for my throttle cable;

And here is the bracket as it was on the old motor/intake for the 2 barrel

 

[steeler85048]

Re: Mercruiser 5.7 Thunderbolt V issue

I also had to MacGuyver the oil resivoir holder by welding it onto the valve cover because the Vortec intake did not have bolts to allow it to be bolted down as it was on the old motor.

Here you can see that the throttle cable is at an angle

But once I put this cable attachment pin on the carb from the original 2 barrel it was straight...

 

[steeler85048]

Re: Mercruiser 5.7 Thunderbolt V issue

OK so now I tried to start it with the third wire attached to the battery positive terminal but alas, the same as before. It acts like it wants to start but it does not fire. I cranked and cranked and finally got it to fire but only runs briefly but stalls and backfires badly.

Very frustrated but would like some ideas as to what else to check. So dejected its not funny!!!! Arg

Any suggestions of where to start before I yank out this Thunderbolt system and send it to meet Davey Jones?

Philip

 

[steeler85048]

Re: Mercruiser 5.7 Thunderbolt V issue

Getting close to ordering

 

[MikDee]

Re: Mercruiser 5.7 Thunderbolt V issue

Are you sure your plug wires are correct? The fact that they were installed wrong to start is a big clue there might be something wrong. You would think it would at least idle in base timing mode?

 

[Pete104]

Re: Mercruiser 5.7 Thunderbolt V issue

MacGyver is an understatement!!!

How much cam does this VORTEC have in it? Have you pulled the plugs to see if your pulling water in thru the exhaust? Are you using the original exhaust manifolds? They maybe cracked as well.

 

[steeler85048]

Re: Mercruiser 5.7 Thunderbolt V issue

yeah I checked the plug wires twice to be sure. It actually started and ran with the old battery before I replaced it and put in two new ones... So, am going to un-hook one battery and put it back the way I had it when it ran.

Was going to take a few plugs out to see if I ingested water and am going to replace the exhaust manifolds now just to be safe.

It's tough not knowing what the previous owner did to the ignition/motor so I'm kinda running blind troubleshooting this.

AS for the cam, its a factory truck cam and it is very close to the marine cam, In fact it has less overlap than the marine Vortec roller cam.

 

[Bt Doctur]

Re: Mercruiser 5.7 Thunderbolt V issue

Lets just start with the basics of starting a new build.
Dosent matter if one or ten batteries , positives to positives, negatives to negatives. you wouldnt be the first person to have batteries backwards
#1 piston at TDC compression.
remove dist cap, rotor should be pointing to #1 cap position.Yes/No
If No, repin the dist to correct to proper position.
looking at the motor ,the right side is 1,3,5,7, the l left side is 2,4,6,8 Dist turns clockwise so start at number one and go 1,8,4,3,6,5,7,2

 

[steeler85048]

Re: Mercruiser 5.7 Thunderbolt V issue

Bt thanks,
I have checked a couple of times regarding firing order and #1 on top dead center. also checked and re-checked plug wires as I have had plug wires crossed before. The weird part is that the engine started and ran before I pulled the outdrive and replaced the seal carrier under the water pump. I also replaced the single battery with a two battery set-up. The P/O had a two battery setup installed previously with a large selector switch allowing either battery single or both.

The only issue I noted is that I mistakenly left one wire off the positive side of one battery. I am also positive I have the distributor stabbed right as I re-checked it.

Could the ignition module be fried because I left one wire off?

Things I am going to try;

1) I am going to try disconnecting the tach lead
2) Check the voltage of the purple wire at the coil and the switch
3) check to see if the purple power wire is connected to the gauges from the switch and if so, if there are any loose wires on any of the gauges
4) RE check all of my battery connections
5) I don't have the tester required for the test called out in the manual by disconnecting the wires from the distributor and touching them rapidly while checking for spark at the coil. But I will work on getting one over the weekend.
6) Check the ground at the distributor from the ignition module.


any other ideas would be very welcomed....

Thanks everyone.....

P

 

[Bt Doctur]

Re: Mercruiser 5.7 Thunderbolt V issue

Is there gas in the carb? Are you pumping the throttle while cranking? There not like todays cars.
The only wires you need are the large positive one and the large negative one. Any others should not matter.
With key on, check for power at the + side of the coil
With key on, chech for spark by pulling coil lead and holding it a 1/4 inch from a good ground.

 

[steeler85048]

Re: Mercruiser 5.7 Thunderbolt V issue

Yeah, pumping the throttle and have a fuel pressure gauge. I get right around 6 psi from my electric fuel pump. I have worked on lots of carbureted cars so I'm familiar with pumping to start

I checked and have spark at the #1 plug so would lead me to believe that its getting spark at the coil. I am also going to go over the timing one last time to make tripple sure as I can think of no other reason for this to back-fire other than if the timing is off... Going to pull #1 plug and ensure i'm on compression stroke and set to TDC and ensure its on #1 at the cap/rotor...

Philip

 

[steeler85048]

Re: Mercruiser 5.7 Thunderbolt V issue

Won't have time to get to all of my list today or tomorrow but will do Sunday...

My Saturday starts with working overtime from 0700 to 1400 then off to an "off duty" gig from 1500 till 0100...

 

[Fun Times]

Re: Mercruiser 5.7 Thunderbolt V issue

What wire did you leave off the battery? Doubtful you damaged the module. Maybe a wire pin has been slightly backed out of one of it's connectors from all the moving around. So be sure to pull and check all wire connectors.
Since it's trying to start suggests it has spark but you need to know if it has enough 12v power to have a strong enough spark to do it's job and be sure it's getting to all 8 spark plugs. And at the right time.

When you went to the Gen+ (Vortec), did you remove one open 90 degree fitting from the rocker cover and install one new PCV valve? All the Gen+ engine models went to a PCV valve while the non Gen+ was open fittings. This may be a contributing factor here.

See item number 8.
http://www.mercruiserparts.com/Show...bnbr=160&bdesc=CYLINDER+HEAD+AND+ROCKER+COVER

I decided to replace it with a chevy 5.7 vortec motor

Was this a new block or rebuilt? If rebuilt, Do you know if a GM degree wheel tool was used to set camshaft timing?

How did you adjust all the hardware under the valve covers?

 

[steeler85048]

Re: Mercruiser 5.7 Thunderbolt V issue

I'm not sure what the wire went to and did not chase it down, I just re-connected it.

This is a used engine that ran fine with very low time. I had to switch the intake from throttle body to vortec carborated but that is the only change. I'm running a freshly rebuilt 4 barrel Quadrajet from a 5.7 Volvo Penta.

I did not know about the valve cover PVC valve. I am not sure why you would only have one PCV as I would think it would it would simply allow any blow-by pressure to leave the block from the other one if its open? Also, this is simply blow-by gasses leaving the block right? Would it affect vacuum?

 

[steeler85048]

Re: Mercruiser 5.7 Thunderbolt V issue

Thanks for the ideas, Will trace that wire down and update then check all of the connectors and go thru the littany of things I wrote down in my previous post on Sunday...

This troubleshooting is sooooo much fun... I can't imagine ever wanting to actually go boating and use the boat on the water as it's so much more fun working on it !!! :laugh: :laugh: :laugh:

 

[steeler85048]

Re: Mercruiser 5.7 Thunderbolt V issue

OK,
So I tested the + side of the coil and found 12.48 volts. I also got 12.48 on the negative side though?? Not sure as I thought this was ground. I then checked the distributor and found 12.48 there as well as at the back of the tach. I also could not find the gray lead for the tach as was posted on a previous thread to disconnect. Is there no gray lead coming from the motor as I thought? I am guessing I got a TB 4 thread confused with the TB 5 system as I could swear someone said to disconnect the gray lead coming from the shift interrupter switch...

Anyways, still pluggin along with troubleshooting.