Heat Sink Paste. Can you use too much?

[CWhalenSHO]

Classic crank no start symptons.....

I just did a top 60K. Car ran fine before I did the maintenance.

I removed the DIS from the intake in order to paint the intake. I masked of all the correct places. (Ground connection on the back on the intake, DIS area, TB area, etc).

The car won't start now that it's all buttoned back up. I know the ground strap at the back of the intake is solid. So my only other thought is that maybe I used too much heat sink paste on the DIS.

Anyone have any suggestions? What else would cause a car not to have spark? I have fuel, I can hear the fuel pump prime.

So, could I have used too much heat sink paste?

Thanks in advance.

 

[Kens1992mtxSHO]

I applied it in dots along the four corners and evenly spaced them throughout the DIS plate. You want to use enough, but not so much that it's oozing out of the back when it's bolted down. Even then... all you've got to do is wipe it off.

The metal on the DIS does need to touch the intake, so I'm guessing it's possible to have used too much.

 

[Mr Anonymous]

Don't forget that where the two crossover tube bolts go that you have to have a good ground path through the tube to the two brackets to the surge tanks. That's a common thing that people miss when painting intakes.

Generally, too much heat sink compound shouldn't be a problem as long as the lower DIS bolts contact the outside metal on the module.

 

[CWhalenSHO]

Don't forget that where the two crossover tube bolts go that you have to have a good ground path through the tube to the two brackets to the surge tanks. That's a common thing that people miss when painting intake

I'm assuming your talking about the two intake support brackets? If so, I bet that's where my problem is.....

I'll give that a shot and report back later.

Thanks for your suggestions!

 

[Off Road SHO]

No, I think Chris is talking about the three-bolt brackets that hold the crossover tube. They get painted over and paint is a great electrical insulator.

The DIS mounting screws are what ground (bond actually) the DIS's backplane to the crossover tube. The two bolts of the crossover tube then bond the crossover tube to the 3-bolt brackets (one on each end). Two of the three bolts of the 3-bolt bracket go into the side plenum, thereby bonding to it. Then the passenger rear intake support gets mounted to the intake with a stud/bolt. The braided grounding strap (and a bracket that cradles part of the wiring harness) is attached to that stud/bolt. The other end of the flat strap attaches to the unibody firewall.

HTH.

Tom

 

[SHObill]

No, I think Chris is talking about the three-bolt brackets that hold the crossover tube. They get painted over and paint is a great electrical insulator.
The DIS mounting screws are what ground (bond actually) the DIS's backplane to the crossover tube. The two bolts of the crossover tube then bond the crossover tube to the 3-bolt brackets (one on each end). Two of the three bolts of the 3-bolt bracket go into the side plenum, thereby bonding to it. Then the passenger rear intake support gets mounted to the intake with a stud/bolt. The braided grounding strap (and a bracket that cradles part of the wiring harness) is attached to that stud/bolt. The other end of the flat strap attaches to the unibody firewall.
Tom

Exactly! That very often problematic ground path is why you should not rely on it. DIS wiring schematic shows the rear lower DIS mount is primary ground & the front lower is also a ground. IMO it is best to run a separate ground wire for these 2 mounts to the strut tower as a ground. Then you will never have a question on the DIS ground.

 

[Brett]

Don't forget that where the two crossover tube bolts go that you have to have a good ground path through the tube to the two brackets to the surge tanks. That's a common thing that people miss when painting intakes.

Generally, too much heat sink compound shouldn't be a problem as long as the lower DIS bolts contact the outside metal on the module.

Guilty.

 

[CWhalenSHO]

I have the rear ground strap attached. I'm thinking that I need to grind the paint off all the three bolt brackets. (the ones that Tom described above. They attach the plenums to the crossover tube). The trusty dremel will get workout tomorrow making quick work of removing the paint on the brackets.

I'll get to work tomorrow night and report back.....

Any other suggestions for what I might be forgetting/need to look at?

I greatly appreciate everyone's help!!!!

:thankyou:

 

[sdpatt]

I have seen powder coating of those bolt flanges to cause poor running due to the bad ground to the DIS. It definitely will cause a problem. I hope it is that simple for you.

 

[SHObill]

For the DIS ground- with all those dis similar metals contacting each other in so many locations, corrosion does happen. Its so much easier to add a separate ground! Esp if your intake is painted or PC'd. & for those weight savers, you do not need all those brkts & bolts holding on the crossover, just the hose couplings are enough.

 

[CWhalenSHO]

Update...Crank, Spark, Fuel pump on

Car is cranking, I'm getting spark, and when I turn the key to ON, I can hear the fuel pump turn.....


So what in the world can be wrong after only doing a top 60K?! I'm at a loss at this point. I'm ready to just buy a bunch of steaks, beer and invite anyone/everyone from the forum to come over to lend a hand.

Eat, drink, be merry. Pass out at the house if you want. Mi Casa, Su Casa.


Now that I'm done venting, I'm open to ideas. Crank, fuel, spark and STILL no start!!!!! What have I done (or not) that would be causing this?

 

[93rev2sev]

only one thing missing. Compression.

Verify.

 

[Mr Anonymous]

I still bet it's a ground.

Just seeing spark doesn't mean it's sufficient enough for combustion.

And the fuel pump priming doesn't mean the fuel injectors are firing and fuel is part of the combustion process.

For giggles and grins, try starting the car with the throttle wide open and see if it tries to catch then. It's an outside possibility all your starting attempts have left a excessive amount of fuel in the cylinders preventing combustion.

As Bill suggested, running a separate ground to one of the lower bolts on the DIS module is a quick way to see if grounding is your problem. I wouldn't however recommend that as a permanent solution.

 

[CWhalenSHO]

Update....Still isn't starting!!!

That was my initial thought as well.....Where I'm perplexed is that she started up without issue before I did the top 60K...Why would compression be an issue now?

I didn't mention that she hasn't been started in almost a year. Could it be the gas in the tank (maybe 1/4 tank) is now garbage or have I done more harm than that?

 

[93rev2sev]

I just re-read. Top 60...

Right.

It's a vacuum problem. remove and reinstall intake...and don't pinch any hoses or wires.

 

[SHObill]

mmmmm... try giving the CCRM a sharp smack & try to start it again. I have had those relays stick on me & just crank, but its usually been after a shutdown when she was hot. Still worth a try.

 

[Off Road SHO]

Oh.... sat for a year eh? Could be condensation build-up in the fuel tank. Water could be the culprit. With only 1/4 tank of gas in it, it has had 3/4 of a tank of moist air condensing every night in there. Open up the return line and cycle the fuel pump a few times into a glass jar. I'd bet you get a lot of water out of there.

Tom