Intake Manifold Leak Symptom and Manifold Gasket Leak Tips
There are many cars that have suffered intake manifold leaks, and still do, so you need to know what intake manifold leak symptoms are like. Also, here are some manifold gasket leak tips to help you.
Ford and GM cars have manifold problems on the V-6s and V-8, in particular; also, there are Mustang manifold problems and GM intake manifold problem on the 3.1 and 3.8 liter engines. In fact, a class action law suit was started against GM by many disgruntled customers. The problem for customers is that the manifolds can leak. Here are some manifold gasket leak tips and details of intake manifold leak symptoms. But first why is there a problem?
There are two reasons why there are these problems: First, they take the coolant through the front of the manifold to get it to the radiator; Secondly, the intake manifolds are molded from plastic.
Plastic manifolds and V-type engines not good idea
The situation is made worse because the engines are V-type units, so the manifold has to for a bridge between the two heads. Although the heads are machined with precision, the angles of the various faces are not always exactly the angle they should be, so when the manifold is bolted down, there is a danger that the manifold is being distorted to fit the faces – this cannot happen with an aluminum manifold.
Mustang manifold problems
This why there are so many mustang manifold problems and GM intake manifold problem. They are all to do with plastic manifolds. Ford, GM and other auto companies went to plastic for intake manifolds to reduce cost and weight, and some cases they did not allow for the problems in the situation. The plastics used can withstand the temperature of the cylinder heads on an in-line engine, but with a V-8 there is a lot of heat coming up to the manifold, which makes it worse. Of course, the under-hood temperatures of modern engines are very high owing to the catalysts. This also makes intake manifold problems more likely.
The other problem is that with a V-type engine you have to take the water from two cylinder heads to one thermostat and then to the radiator. The easy way of doing it is to put some outlets in the side of the head, and put mating passages into the manifold, connecting to the thermostat in a cavity at the front of the manifold.
With an aluminium casting that is a straightforward solution, which simplifies the design, but is still prone to leaks if the faces are not aligned correctly. However, it is a very different matter with plastic, because one end of the manifold has to cope with the temperature fluctuations in the cooling system, and is under attack from any harmful elements in the coolant.
For these reasons, plastic intake manifolds that have water passages built in are prone to cracking. In some cases, Ford has switched back from plastic to aluminum.
Intake manifold leak symptoms
Intake manifold leak symptoms are pretty obvious. If there is a leak in the coolant passages, water or steam will leak out and should be visible either when the engine is idling, or with a puddle that forms when the engine is parked. Take a look underneath when you park the car if in doubt. Other intake manifold leak symptoms include a lowering of the water level in the top tank. If that keeps falling you have a leak somewhere. At least a leak in the manifold is better than a leak in the cylinder head – much cheaper to replace.
If possible replace the manifold with an aluminum one. You can after-market manifolds or manifold spacers that are not only stronger, but can give more power.
Intake manifold leaks can also occur in the actual intake branches, or more likely you have a manifold gasket leak. Here are manifold gasket leak tips. If you have a leak, the engine will be uneven or rough at idle – it just won’t idle smoothly. You may also hear whistling or sucking, as the engine sucks air in through the leak, be it a crack or a leaky gasket.
You can use a vacuum gauge to check the manifold pressure, but an easier way of finding a leak is to get a small propane gas cylinder from a hardware store, and get the engine running. Then you squirt a little gas along the edge of the manifold joint. When you find the leak, the gas will go in through it, and the engine speed will rise, and then be smoother. Now you know where the leak is. Then, you will need to remove the manifold, first draining the coolant system, to correct the problem. I hope you find these manifold gasket leak tips useful.
Leak on top of SBC 350 intake manifold
When check my SBC 350 after driving home from work I find a small pool of antifreeze on the intake manifold near the water neck. It looks like the leak is either from a bad seal between the water neck and the manifold, or from the bottom side of the upper hose where it fits over the water neck.
The manifold is an Edelbrock Performer EPS, and I’ve tried both the original water neck from my ‘75 iron manifold, and a replacement water neck from the parts store. I used a stock gasket and some red permatex. Radiator hose is not new, but is in good condition and the clamp is tight.
I’ve had the minor leak for the last couple of years, and I’ve finally decided that I have try harder to get it fixed. I will again use a new gasket and sealer on the water neck and a new radiator hose, but what else should I check? Could the manifold surface be that uneven where the water neck bolts on, or could water be coming through the manifold casting? I don’t want to use any sealer between the hose and the water neck because it will be too hard to replace a hose later on, but is there any other way to improve the seal?
I have a 1999 Yukon 2WD with the 5.7 lt engine. There is coolant leaking out of the intake manifold just behind the alternator. It is coming out of the gasket where the manifold mounts to the engine block. How hard of a project am I getting myself into? I am fairly competent and have worked on a lot of engines in the past when I used to buy/sell used cars. That was 15 years ago and now it looks very complicated. Could I be biting off more than i can chew? Are there any big "pit falls" I need to be aware of? I will not do it myself if I have to disconnect A/C lines.
Thank you!
1996 Mustang GT~2 Interesting Problems!
1) I have an antifreeze leak that seems to be coming from between the engine and tranny. I got underneth and saw it was coming straight down the middle of the engine/tranny mating surfaces. no alien blood on the sides of the engine/tranny mating surfaces, and none on top. I’ve crawled all on top of the engine with it running and off to look at the very back to see if it was coming from a heater hose, or the one that goes under the intake manifold. when I bought it from my friend, he had installed a deeper Ford Racing Intake Manifold, so i wasn’t sure if that was it.
I don’t see any antifreeze in the valley under the intake manifold, either front or back. Logic says that it’s a bad freeze plug on the rear of the motor. BUT, problem is, it only really starts to leak when it gets hot enough to open the thermostat (at least I think so, and from what I observed.) am I right, or anything I missed? alo, how can this happen if all the other steel plugs on the side of the block are fine?
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