Hello all, I have a '93 Dodge Dakota 5.2 V8 with about 137,000 miles. I made a previous post about a week ago describing my issues of low rpm, rough idle from time to time, airflow diverting to the defrost when accelerating, and my coolant reservoir magically drains itself. "Ol' Grouch" on here helped me a lot and confirmed my suspicions of a vacuum leak. I do have a suspicion what the issue is with my coolant, though I'm not too sure how to fix it, it should be simple.

Anyway I took it to a shop and they tested and inspected the vacuum valves and hoses. All was in working order but they too thought it was a vacuum leak they just couldn't find it without a smoke machine which they did not have. They recommended me to a another mechanic who they thought would have one. He didn't, and he wasn't convinced that it could be a vacuum leak, at least for all of my issues. Especially the low idle; he said usually with a vacuum leak they idle high. I had read the same thing a while back online. I called my original mechanic back and asked them if they checked the manifold, maybe it just needs to be retorqued as Ol' Grouch had suggested with my previous post. They just didn't think that it would be likely that is the problem. So anyway, before I dump a bunch of money I'm still trying to gather info and theories. I'd almost sacrifice my left nut by this point to gain the knowledge, tools, time, and space to just tear the thing apart myself and rebuild it lol.

And one last thing I forgot to mention in my last post is pretty dang weird: if I'm in motion and I put my windows up or down, my airflow cuts in half. Somehow the electrical of my windows is interfering with the airflow in my vents. It doesn't do it if I'm driving real slow or in park and it's only done it maybe once or twice that I've been able to notice. So is it a fuse or something? Some kind of electrical problem? I have no idea. I do believe there must be some kind of vacuum leak but if nobody in my town has a smoke machine and the valves and hoses are good, how do I go about fixing it? And are the more issues at play than just a vacuum leak?

 

Hello all, I have a '93 Dodge Dakota 5.2 V8 with about 137,000 miles. I made a previous post about a week ago describing my issues of low rpm, rough idle from time to time, airflow diverting to the defrost when accelerating, and my coolant reservoir magically drains itself. "Ol' Grouch" on here helped me a lot and confirmed my suspicions of a vacuum leak. I do have a suspicion what the issue is with my coolant, though I'm not too sure how to fix it, it should be simple.

Anyway I took it to a shop and they tested and inspected the vacuum valves and hoses. All was in working order but they too thought it was a vacuum leak they just couldn't find it without a smoke machine which they did not have. They recommended me to a another mechanic who they thought would have one. He didn't, and he wasn't convinced that it could be a vacuum leak, at least for all of my issues. Especially the low idle; he said usually with a vacuum leak they idle high. I had read the same thing a while back online. I called my original mechanic back and asked them if they checked the manifold, maybe it just needs to be retorqued as Ol' Grouch had suggested with my previous post. They just didn't think that it would be likely that is the problem. So anyway, before I dump a bunch of money I'm still trying to gather info and theories. I'd almost sacrifice my left nut by this point to gain the knowledge, tools, time, and space to just tear the thing apart myself and rebuild it lol.

And one last thing I forgot to mention in my last post is pretty dang weird: if I'm in motion and I put my windows up or down, my airflow cuts in half. Somehow the electrical of my windows is interfering with the airflow in my vents. It doesn't do it if I'm driving real slow or in park and it's only done it maybe once or twice that I've been able to notice. So is it a fuse or something? Some kind of electrical problem? I have no idea. I have no doubt it must have a vacuum leak, but no mechanic has a smoke machine in my town and the valves and hoses, how do I go about fixing it? And could a vacuum leak be responsible for all of my issues or is there more at play?

 

If you are going by the tachometer you should know they are notoriously inaccurate.
You can get a torque wrench, either buy it or rent it from a parts store, and re-torque the intake your self. There should be a diagram on here for what order to do it in.

Here the bottom of the page shows how to torque the intake.
https://hughesengines.com/Upload/pro...G7720R0919.pdf

 

Ah yes, thank you. Honestly that makes sense because 99% of the time even at "400" rpm it seems to idle smooth and runs good. Once in a while though it will idle a little rough and gradually smooth out. But it hasn't done that in a little while so maybe that's just a fluke thing.

 

Let's go old skool here. Let's do some basic troubleshooting like I learned in the 1968-70 era. Take your air cleaner assembly off so you can access everything. Use a spray can of WD-40 if you can, or just a spray bottle of water if you don't have any handy. With the engine running, spritz (<----fancy technical term) around the base of the throttle body and along the sides of the intake where it meets the heads. If the engine speeds up when you spritz (<--------that fancy technical term again) and area and the engine speeds up or smooths out, you've blocked the leak for a moment. If seen a leaky throttle shaft respond this way too. This will track down a seeping gasket or loose connection.

Run your mark 1 eyeball over the vacuum lines while you're at it. You may have a cracked vacuum joint somewhere. If you think this is a stinker, I used to have a 1982 Mercedes 380SL with the vacuum controlled computer. There's a reason they don't use vacuum controlled computers anymore.

 

i had a vacum leak i was struggling to find on my dakota and only found by accident . i sprayed a wasp with brake clean on my brake booster and engine changed rpm . it turns out my leak was around the bolts on brake master cylinder. probably a 1 in a million type deal but worth checking

 

If the plenum gasket is leaking you won't find that by spraying. Open the throttle blades and look down and see if you have oil at the bottom. How old and what condition is your battery? Weak batteries can cause low or no idle. The iac also may be on it's way out. Have a look at your water pump, Underneath it there is a small hole. If the pump is starting to leak you will see signs of coolant leaking out. I will be slow and evaporate before hitting the ground. Wouldn't hurt to look at the hose connections either, It could be leaking there also. Airflow diverting to the defrost vents is caused by low vac levels. This is common and could be a bad check valve/s or a leaking line/actuator.

 

Duplicate post. https://dodgeforum.com/forum/1st-gen...-problems.html