Intake Manifold Gasket Leak

[Andy]

Hey all,

I have a 1989 mazda 323 with an E5 engine. i had a misfire and found that my intake gasket was leaking. so i proceeded to change the intake gasket. bought the new one took out everything to access the bolts took it down. after which i cleaned everything by scraping off the big chunks as much as possible and then wire wheel bit on a drill to clean off the rest, was not perfect i woulda say but it was clean especially around the intake ports and the water ports. then i used some gasket shellac on the gasket and mating surfaces and put everything together. Now instead of just leaking on top behind cylinder 2 it leaks everywhere all on top and below as well. i have no clue what i did wrong.

Topic

[Rob megee]

Boy I hate it when stuff like this happens. You may to need to pull it all apart and recheck your work. As far as ideas, I have had things like wires, vacuum tubes etc, get in the way and have tightened the manifold down against them, it won’t seal and leaks everywhere. Try to look and make sure the two surfaces are mated flush against each other. If you didn’t get all of the old gasket material off that could be causing the issue. You can borrow a radiator pressure tester at most auto parts store and pump up the radiator pressure a little, to see where the water starts leaking from. You also might not have aligned the gasket correctly, sometimes it’s hard to tell if they are flipped or even upside down.

[Steven Cummings]

It is possible when you were dropping the manifold back in, the gasket slipped a little, maybe not even a millimeter, but that’s enough on some engines. The other things that could be were tiny bits of gasket left behind. Also, were you using an accurate torque wrench for these? If one side is too tight, while the other isn’t tight enough can cause this type of problem.

[Andy]

I am pretty sure that nothing got in the way, as for slipping i placed it on the studs and it fitted snug, i also checked to make sure i put it the correct way as there was a single extra hole on one side, there was very little of the older gasket materials remaining and thats also why i decided to use the shellac to help. So i took it down again to recheck my work and everything i said above was true. the shellac also seemed to have sealed it nicely. i was unsure what to do so left the gasket that came off on the manifold side on their and cleaned the head again and then i used grey rtv silicone ( i know its not a good idea as it will dissolve in the gas but i tried it just to see if it would seal for a little bit) and this did not help. i put everything back up and it still did not work same problem leaking everywhere. i then just wanted the car to at lease run so i took the rtv and filled to reachable top part of the manifold seam where it meets the head with silicone and only then did it seal on the top part but i am not feeling satisfied with this and it it still leaking on the underside. I dont know what to do anymore

[Steven Cummings]

🙁 We do understand your aggravation. On the bright side, you’ll be able to tear down to the manifolds faster than most people!

I should have asked if your manifold surfaces are square. Has the car ever overheated though this will rarely ruin iron heads/manifolds, age can. It could be that the old gasket had deformed with the mating surfaces, while the new one doesn’t want to. I don’t think this is the problem, but one thing to add to your list. I don’t know if this uses the aluminum engine/manifold. I know some older Mazda’s did because of the weight. If it does use aluminum, then a wire wheel could have seriously messed up the sealing surface, and you’d need to get everything resurfaced.

Were you able to compare the old and new gaskets? Were they an exact match? Not that you want to spend more money, but what about trying a different brand of gasket (i.e. Fel-Pro vs Victor Reinz). While most gaskets are fine, sometimes one just works better than another.

Mostly, you need to make sure there is zero gasket material left behind, some sealing surfaces are highly sensitive to this. You can try lacquer thinner to help soften up your old gasket material. Also, don’t use any gasket sealing materials unless specifically called for by the FSM (this includes shellac and RTV).

[Steven Cummings]

I did a small search, and it looks like your block might be iron and the heads and manifold might be aluminum. If your heads and manifold are aluminum, they may have become scratched by the wire wheel you were using. This would cause the poor sealing you’re having now. Someone more familiar with the E engine will know (Mazda has a lot of engines!)

IF the above is the problem, then your most appropriate solution is to have the mating surfaces resurfaced to the proper roughness. Something some people swear by is the copper spray that you put on your gaskets that can help it seal on rougher than spec surfaces.

First try to have your surfaces COMPLETELY clean (no gasket at all), check for squareness and make sure you have no gouges/major scrapes. Then make sure you torque everything to the correct value and in the right sequence.

[EricTheCarGuy]

You should never use a wire wheel on aluminum surfaces. The scoring caused by that can cause leaks. If this is what you did, this may be the cause of your leak. You should only use plastic on aluminum surfaces to avoid the scoring I mentioned. Also, it’s not good practice to add any sealant to a gasket. “Let the gasket do the work”, is what you would normally go by. Only add sealant in areas recommended by the manufacturer, and only in the places and amounts specified. Only use the manufacturer recommended sealant as well. Sometimes the use of sealants can actually cause leaks. Lastly, over tightening. If you got the fasteners too tight it can warp the metal and cause a leak.

As suggested you may want to go back over your work to make sure everything is correct. In order to fix the scoring, if that is indeed what you have, you’re likely going to have to take the part to a machine shop to be re-machined so that it seals properly.

Good luck and keep us posted.

[Andy]

Ok so i really messed up here. I do believe now that the wire wheel i used scored the surface and i will have to get them resurfaced. thanks everyone for your input. at this moment i just pasted silicone on the outer seem where it seals and leaks and it has temporarily helped on the top part so i can drive the car. I will attempt to have them resurfaced but i dont know if i will find anyone to do it yet (my country sucks with regards to these things) and hope it works out will keep you all posted.

[Steven Cummings]

Wish you the best in finding someone. You can just take it to any machine shop that has a milling machine (usually 16 ton) and let them know what roughness (or lack thereof) you want; the machine shop doesn’t necessarily have to be specific to cars. I don’t know the exact specs, but I think for aluminum it is generally between 40-60 RA, though every manufacturer will have different specs. Hit up a Mazda forum for your best answer.

[Author]

Replies