Water leak

[DavidM]

The car started running pretty hot towards the end of the last race so I slowed down and was able to finish the race without losing a position (I was pretty far ahead of the guy behind me). I was able to keep engine temps around 200. Anyways, I got myself a coolant system pressure tester and it looks like the leak is where the intake manifold connects to the engine block. Is it common engine design to have the coolant line run through the intake manifold to get to the block? To make matters even more fun, I was checking to see if the intake manifold bolts had worked loose by giving them a turn with the ratchet and snapped the head off one of the bolts (without much effort).

So, is this a common problem? I'm wondering if the bolts were old and fatigued and had loosened and that's why I was getting a leak. I may be able to fix the leak by just replacing the bolts and re-torquing, but I'm wondering if I shouldn't just take the manifold off and redo it. It looks like RTV was used as the gasket for putting the manifold on, but the manual seems to show gaskets. Is it better to use the gaskets or the RTV or does it matter? What about the bolts? Should I just order some from the dealer or are there better ones to use?

The manual doesn't show jack on the manifold other than in the one drawing with the entire block. It looks pretty easy to take off (other than having to get at the bolts underneath), but are there any gotchas I should watch out for? I'm probably most concerned about my ancient wiring and breaking wires when I move stuff around.

Any and all help/info/suggestions are welcome. Thanks.

David

[zracre]

best bet is to remove the manifold...It has been a long time since I worked on the KA24E but I remember it being not so bad...just watch for extra wiring and stuff under the manifold. Also use factory pieces. when the manifold is off check it with a straight edge to be sure it isnt slightly warped.

[lateapex911]

David, I don't know your car, and I don't make a dime as a mechanic, and I didn't even stay in a Holiday Inn last night, so take what I say with a grain of salt as coming from a guy who wants to help if he can.

It is common for engine coolant to pass thru the intake manifold to heat the intake air ......and it's common for a leak to develop and corrosion to result.

If they sell a gasket for your application, buy it! It might be in a kit that includes O rings and whatnot. Use them when appropriate. Clean the mating surfaces with a straight blade, carefully, so as not to scratch them. If there is corrosion, get a flat stone to clean it up. Some guys just wing at it with a grinder. That can work with the right wheel and touch, but it can also go wrong. You want flat surfaces to mate well.

The intake/head interface may have been port matched. If so, ensure that you reassemble so they line up properly.

Your manual should spec a torque for the bolts, and I would source new or known good versions of the bolts to replace the existing. You'll have to "esay out" the remainder of the broken bolt, unless you can get a vice grip around the protruding shaft. If you can't, the guys at a good parts strore can help set you up with the right tool if you don't already have one.

Be sure to start the job at their opening time, so you can complete it before their closing time!

[erlrich]

So, is this a common problem? I'm wondering if the bolts were old and fatigued and had loosened and that's why I was getting a leak. I may be able to fix the leak by just replacing the bolts and re-torquing, but I'm wondering if I shouldn't just take the manifold off and redo it. It looks like RTV was used as the gasket for putting the manifold on, but the manual seems to show gaskets. Is it better to use the gaskets or the RTV or does it matter? What about the bolts? Should I just order some from the dealer or are there better ones to use?

The manual doesn't show jack on the manifold other than in the one drawing with the entire block. It looks pretty easy to take off (other than having to get at the bolts underneath), but are there any gotchas I should watch out for? I'm probably most concerned about my ancient wiring and breaking wires when I move stuff around. [/b] David - I've never had any problem with leaking in that area, but I can see where there is the potential. And yes, there is a gasket between the manifold and head, I would strongly recommend putting a new one on. Also, there are several small water hoses on and around (and under) the manifold, this would be a really good time to replace all of those. In fact, since one of the heater hoses runs to the block under the back of the manifold it sure wouldn't hurt to replace those while you have the manifold off.

As far as gotchas, there's nothing too terribly bad, just a few little PITA things you have to deal with. First, there is a bracket on the underside of the manifold you'll have to take loose. I usually unbolt it from the manifold and just loosen the bolt at the bottom and it will move enough to get the manifold out. Second, there are a bunch of vacuum lines running to/through the manifold; I usually mark the ones that I haven't plugged, but if you don't want to bother there's a pretty good schematic on page 7 (1990 FSM) of the emission controls section of the manual. Third, I've always had to separate the top collector from the main manifold in order to get to that rearmost long manifold bolt, but I have had at least one guy tell me he can get the bolt out without doing that. If you find you end up having to take the collector off you will probably also need to replace that gasket when you put it back together.

That's about all I can think of - since I just had to pull the head a few weeks ago I would hope it's still pretty fresh in my mind.

Oh, and I would definitely go ahead and replace all the bolts; if one broke (and they shouldn't break that easily) I wouldn't trust the others. JMHO though.

Good luck - let us know how it goes, or if you run into any more problems.

[bilracer]

Call Riley Curtis up at Lynchburg Nissan in Va.
he has an aftermarket gasket that is alot better quality.

[Tristan Smith]

Just pull the Intake, clean up everything, use a new gasket and put RTV on both sides of it (Around the water jacket) , Bolt it back up. More than likely the seal went away, causing the leak.

[DavidM]

Thanks for all the info guys. I went by the dealer today and order some gaskets and all the bolts, studs, nuts, and washers. The dealer parts drawing shows screw in studs with nuts for the outter most holes holding on the manifold. It just so happens that the bolt I popped the head off of was one of those holes. So at some point the stud was removed and just a bolt used. I think that may have contributed to the mainfold working loose. I also found that the bracket underneath was not bolted to the manifold, which may have allowed more vibration than normal. I'll see how things look when I get it off.

David

PS: Anything special to screwing in a stud? Is there such a thing as a stud-screw-in tool? Should I use one of the weaker lock-tites on it?

[lateapex911]

One trick to getting a stud in is to double nut it. That is, put two nuts on the outer threded section, and use two open ends to tighten them against each other. Now you have a bolt. Use the outer nut to install it, then use the open ends to seperate them and remove them.
I'd use red locktight.

[its66]

David,
It has been a while since I raced my 240, but here is what I remember.

Install that suppport bracket for the intake manifold. I had an intake crack and I'm sure that missing bracket contributed to it. That intake is fairly heavy and needs the support. Check it for cracks while it is off the car.

There is a small 1/2 inch-ish(is that a word?) elbow shaped bypass hose under the intake below the T-stat. I remember it giving me trouble several times when putting everything back together. It was difficult to get it to seal properly.

I always used the factory gasket with no problem. I was able to remove the intake as one piece without separating the two halves. It is awkward, but not too bad.


Not much different that Tristan or anyone else said, but maybe it'll help.....