Cooling hoses under plenum

[breaksr]

Sprung a leak on one of the hoses under the plenum (1991 Q45). Thought it was the hose to the thermostat at first but after replacing that one and driving the car I was still getting some anti-freeze under the plenum. Problem is I can't see which hose it is leaking from under the plenum. Are there more then two cooling hoses under the plenum? I only know of those two fat ones that are in the well over the knock sensors. Also can I buy the hoses from the local auto parts store or do I need to buy them from Infiniti?

[qship96]

If the underplenum hoses are original,the problem is many of them will be brittle from all the years of heat, and the movement of them in the process of removing the plenum will crack,split,and even shatter many of them....why you MUST have every single hose under there on hand ready to swap...and if you intend to keep car awhile, might as well replace ALL of them at once instead of multiple plenum diving. Best to order the mac-daddy hosekit from Joe.

[BLACKonBLACK98]

even the mack daddy kit doesn't contain all of them anymore. 1 hose is unavailable.

[qship96]

A good reason for any owner who has older hoses to purchase the kit NOW, even if they dont need it just yet.....who knows how many more hoses will become unavailable in the future

[maxnix]

even the mack daddy kit doesn't contain all of them anymore. 1 hose is unavailable.

Really? From Joe?

[breaksr]

I'm fully educated in removing / re-installing the plenum. I've had mine off three times and I've had a friends off once so I know about the hoses being brittle. I'm just wondering if there were any other cooling hoses that are under the plenum that I might miss besides those two larger ones that are above the knock sensors. I can't tell if they are leaking but there is some fluid coming from somewhere so it seems those two hoses are the most likely candidate. I just don't want to remove / install the plenum more then once. All of the emissions hoses are still in good shape I replaced a couple of them years ago.

[jimbyjimb]

I can't remember too well as I've only done it once, but I know there is a pair of hoses running coolant through either the TB or intake manifold. They're pretty easy to find if you're looking for them.

[qship96]

I'm fully educated in removing / re-installing the plenum. I've had mine off three times and I've had a friends off once so I know about the hoses being brittle. I'm just wondering if there were any other cooling hoses that are under the plenum that I might miss besides those two larger ones that are above the knock sensors. I can't tell if they are leaking but there is some fluid coming from somewhere so it seems those two hoses are the most likely candidate. I just don't want to remove / install the plenum more then once. All of the emissions hoses are still in good shape I replaced a couple of them years ago.

Why it is suggested to get the mac-daddy kit and replace ALL hoses/KS at the same time.....you are getting ready to remove your plenum for the 4th time because you didnt follow this advice!!!!! In 216,000 miles,my plenum was removed ONCE, and everything replaced{at about 200k},should never need to be removed again under my ownership.

[breaksr]

Okay now your stirring up some memory cells. There are two hoses that connect to the throttle body just over the driver side valve cover. They are long but are very small diameter. That could be the problem. I will check tonight. Thanks.The reason I have not changed all of the hoses over the years that I have owned the car is the cost is astronomical. The car runs great and I really don't feel like paying $40+ for one breather hose. I've found that you have to go easy on the amount you spend on this car given the vehicle is probably only worth about $1500 at best. I do the oil changes every 4K and replace the fluids on a yearly basis and that keeps repair costs very low. I'm still running the original transmission on the car and it shifts better then any other automatic I have ever owned. I can't seem to part with it given the Tokico struts have finally soften up to a point that it's actually a nice ride.

[maxnix]

The car runs great and I really don't feel like paying $40+ for one breather hose. I've found that you have to go easy on the amount you spend on this car given the vehicle is probably only worth about $1500 at best.

What else can you get for $1,500? $3,000? $12,000?

The point is, if you don't allocate the prorated $3K per year to maintain the car, the first big system that fails will cost as much as your car is "worth" to you, and then your car will be worth zero unless the failed system is replaced.

[BLACKonBLACK98]

Really? From Joe?

coorect. i was told "INF 11826-67U15, hose blow by, a" was no longer available and received a refund for that part.

[breaksr]

That $3000 / year that Dennis throws around I think that's for people who bring the car to the dealer. When you calculate the money I spent in the last nine years over 138K miles I come up with about $600 / year. Since I do all the repairs I'm not taking into consideration the labor.Now back to the problem at hand. I found the bad hose it turned out to be the big hose that is in the center of the well. That is a real pain to pull those metal pieces off the heads that connect to those hoses and then seal them back up with new hoses. I put everything back together and when I was tightening the plenum one of the bolts stripped. I hadn't even finished tightening the bolt and it stripped. All the other ones went in fine so everything is tight I'm just wondering what I should do now since the receiving end of that bolt is the intake manifold. Can you put a heli-coil in there or do I need to replace that one intake manifold from a junk yard car?

[goody90q45]

I just put in 6 helicoils with the plenum installed on my 90Q a few weeks ago. I bought a kit at Napa with a dozen helicoils the same size as the plenum bolts. The stripped holes were drilled out with a 1/4 drill and then retapped. You end up taking out very little meat with the 1/4" drill. Rethreading the holes was very easy and all 6 helicoils went right in and are holding tight.

[breaksr]

Okay great. That sounds perfect. I was a little worried since the intake manifold seems like such soft material. Looks like the shape of the bolt makes it possible to install the heli coil without removing the plenum again.