MC Slide Hammer

Hi.

I have a 93 Accord EX. I've been dealing with a rough idle. Thought it was due to a vacuum leak caused by a cut valve cover gasket which I had siliconed close. -- Wasn't the problem, but as it so happens, the vacuum leak is in the same area as that portion of the valve cover.

It's where the intake bolts on to the engine head and where the injectors are. Somewhere right at the side of the valve cover there is a crevice - it's not a crack. It's a crevice where the intake meets the engine head, but there's a vacuum leak coming from there. I was able to shoot throttle cleaner straight into there and stall the engine.

My question is: What's causing the "crevice" to have a vacuum? There is a fuel injector (4th cylinder) nearby.

Is it likely that if I replace the gaskets on the fuel injector, the leak will go away?

Thanks. I hope this long post is clear enough.

Chiovnidca

Sounds like a piece of the intake manifold gasket cracked and broke free. I've seen a few of em do that. Replace the gasket.

nus_dogg

We diagnose a Infiniti QX4 with leaky fuel injector o-rings that threw a random misfire code once the engine warms up. And it definitely can be the injector o-rings. What you can do is spray some soapy water to each injector o-rings and watch for bubbles, and it works. Thats how we confirmed the leak. We also hooked up a smoke machine to find it but soapy water will also do the trick for the o-ring leak.

Good Luck!

Nicefeet

I've never seen a vacuum leak bubble.

MC Slide Hammer

Thanks for the replies.

I already know where the leak is coming from.

I wish I could take a picture of the area, I'm talking about.

But, again, on the intake side of hte valve cover, as you go down that side wall, about an inch or two, where the fuel injectors are, and where the intake meets up to the engine head, metal to metal, the leak is coming from there.

I've purchased a bunch of gasket sets for the injectors. But I'm wondering whether if there is a bad o-ring on the fuel injector, there can be a vacuum leak coming from anywhere where the engine head meets the intake.

Cuz, if not, I'm going to return the gasket kits.

holmesnmanny

When you put the injectors into the intake manifold you have to make sure the insulators get a light coating of oil so they seat properly or it will almost surely leak. You can tell if they set properly because they will not be flush.

MC Slide Hammer

Chiovnidca, thanks for the suggestion.

It looks like you're right. Although, I'm still not sure -- although, if there's a bad o-ring on a fuel injector, a vacuum leak is not going to show up at the seam where the head meets with the intake manifold, right?

So, I'm going to go purchase an intake manifold gasket, 10 bucks at a retailer here.

But I've never worked on that part of my car before. Is replacing the manifold gasket a big job or is there a lot involved for a Honda Accord 93?

Any tips, dos, don'ts, cautions, shortcuts, html links?

Thanks.

holmesnmanny

There are 9 nuts in total, five on top and four under. The nut that's underneath and further on the passenger side you can get using a 3 inch extension from the passenger side of the vehicle. The other 3 nuts underneath you have to get from under the vehicle using a box wrench. Make sure the vehicle is supported properly.

When you tighten remember to torque from the inside out, meaning do the middle nuts first then work your way out.

MC Slide Hammer

So, all I'd need to do is remove those nuts?

And there's room enough to push back the intake and throttle to remove/install the gasket?

What about coolant? Does removing those nuts cause coolant to leak everywhere?

I would really appreciate any response. But no rush.

I've got a full week of work ahead and some appointments. I'll have no time or energy to do this thing this week. Although I might be willing to squeeze it one later afternoon.

When I went hunting for the vacuum leak, I used quite a bit of throttle cleaner, which had the effect of cleaning that area of grime and debris, which in turn had the effect of making that vacuum stronger by clearing the seam. So my car idles pretty much like crap. Runs OK when accellerating, though.

Holmesnmanny, thanks!

phootbag

Make sure the mating surfaces are clean. You can end up with another vacuum leak or a cracked intake manifold.

holmesnmanny

The only time I pulled my intake manifold it was either to take it completely off or when I pulled my engine. I don't have my car with me at the moment. You could first try to tighten the nuts and see if that fixes it. That would be what I would try first. I believe they only need to be 19 ft/lbs so it's not very tight but they could just be loose near the leak. Now that I think of it I think u need to pull the injector rail to get access to the nuts. To do that you would need to take off the three nuts holding the injector rail to the intake manifold. To get access to one of those, I think u need to remove the iacv. When removing the fuel injector rail try lifting it straight out as you want to whole thing to come out. If you don't pull it straight out one of the injectors may stay put and you will leak some fuel which in itself isn't that bad but you want to try to avoid that. Like I said above, when putting the rail back make sure to coat the insulators with a bit of oil so that all four injector insulators go in nice and smooth. There will be one insulator and one ring at the end of each injector where it meets the manifold. Like I said, I believe you have to pull the rail but you may not need to.

MC Slide Hammer

I have access to the top bolts with rail there.

I'm really curious, however, about the coolant. Is coolant going to drain out if I unbolt that manifold?

And I don't think I'll have enough room to pull back that manifold and such. But then maybe I'm wrong.

Keep the tips coming. I appreciate it.

ZROVER

I have a similar problem with my F20B and H22A intake. Idle is tough without the IAC connected BUT revs to 7000 by itself when connected.

I replaced the intake gasket when I attached the intake to the engine so I am leaning toward the gaskets on the injectors. When I spray carb cleaner at the base of where the injector seats with the manifold i get a steady raise in engine speed.

To answer your question about the coolant. You will have coolant spill when you separate the intake. I had some spill even after I drained the radiator and separated the intake. The majority came from the hose that runs between the two though.

nus_dogg

At the o-rings, it bubbles. You haven't, but I have when my instructor told me to spray some simple green onto the injector o-rings after we did the smoke machine test to confirm the leak.

time-stop eg

maybe change the intake manifold gasket and scrape off the old material from the manifold and then to be safe change the injector o rings that go into the manifold.

MC Slide Hammer

Will I need gasket adhesive for this job?

If so, is silicone OK?

PS: I'll be doing this job tommorow afternoon. I'll keep this thread updated. If changing the gasket, doesn't do it, then I'll be chaning the orings on the fuel injectors.

nus_dogg

What I used when I don't have gasket remover, is I use warm soapy water then use some razor blade to scrap the remaining off the head.

I recommend you get the Hondata Intake Mani gasket even though I know you're not going for performance, it'll help you in the near future as this gasket is re-usable.

holmesnmanny

There is a hose that connects somewhere near the number 4 cylinder intake. You can look to see. I can't remember if it's on the intake manifold or not. If so, and you have to pull it to get the manifold off, then yes you need to drain the coolant. I can't remember at the moment.

Now that I think of it, I think you might have to remove two bolts that go through the thermostat housing side into the manifold. You'll see it when you look at it. Then again you might not have to.

MC Slide Hammer

Did the job today. I haven't test drove for too much, but so far everything seems fine, vacuum leak is gone, rough idle is gone.

Replacing the intake manifold gasket turned out to be a major PITA. Never gotten so dirty working on my car, or so cut up. My hands are killing me right now.



There are 9 nuts holding the manifold in, 3 of which must be gotten from underneath; I found the most diffcult nut to remove, the one closest to the thermostat housing, was something I get barely manage to remove from topside. There are 2 bolts that fasten a bracket to the manifold that must be removed from underneath. Both nuts and bolts take a 12 mm socket or wrench.

You must also remove the air filter assembly and get the duct out of the way, since you will need that space to remove the 3 bolts fastening the intake thermostat housing to the intake manifold; the housing is hooked up to the water pipe that doesn't allow movement.

Once all 9 nuts are removed the coolant will drain out. I was told by someone else that not much coolant comes out, WHICH IS FALSE. Pretty much every ounce of coolant drained out.

Getting to the two passenger-side nuts on the underside is extremely difficult. One thing that might possibly have made it easier is to take off the wheels (both sides). I didn't do that for my job but I imagine that would have enabled better positioning.

One replaces the gasket by pushing the manifold to the back -- though easier said than done. Once the nuts are off, the manifold should be wiggable.

This job was difficult for me, the thermostat housing bolts are difficult to get out and back in; and the two bottom-side, passenger side nuts are extremely difficult to remove and place back on; and plus I was going into this job half blind and had to figure out more than a few things.

Also, this job makes it very easy to break something, a sensor, a wire, or a hose. Not to mention that because you work underside for at least half of the time, protective eyewear is highly recommended, and you'll get extremely dirty if you car has a slight oil or engine leak. Not fun.

Anyway thanks for the help. Feel free to ask questions.

holmesnmanny

Actually you don't need to completely remove the bracket, just the bolt where it secures to the manifold. Also, there are two closer to the thermostat, the one further to the left you have to get from the bottom. The other one, you can get with a 3 inch extension from the passenger side.

MC Slide Hammer

If you don't unbolt both bolts on that bracket you give yourself less room than you already have. Is it neccesary? Maybe not, but definitely helpful.

Thanks for the replies.