coolant return line leak

07-04-2010, 06:33 PM
1999 CV............. coolant return (I believe) line from the heater core is leaking below the point where the rubber hose is attached. If I understand correctly, the hose is clamped to a metal nipple that is inserted into the end of a plastic tube that goes under the intake manifold. It appears that the leak is coming from the top of the tube where the metal nipple is inserted into it. Is there any way of stopping the leak without removing the intake to replace the tube. I already tried some Alumaseal in the radiator, suggested by a Zone employee, but that did not stop the leak. I didn't think that it would work as there is no radiator cap, only a coolant reservoir to dump the powder into, so therefore no real circulation to move the product around to the leaking area. The leak is very small at this point; only a tennis ball sized spot on the driveway overnight if the car was driven that day. Any/all comments/suggestions will be greatly appreciated. Thank you.

07-08-2010, 03:48 PM
The hose assembly can be replaced without removal of the intake but it is a pain to get it done. I have seen just a section of heater hose used in place of the tube and had the areas where it touched the engine well insulated with loom and tape. Not the ideal fix, but it worked. You can also fabricate your own hose with metal tube, hose and clamps. You can place the3 metal where ever the hose assembly will touch the engine.

07-10-2010, 08:32 PM
While changing the spark plugs I was able to more correctly identify the location of the coolant leak. It is coming from around the metal nipple that goes into the rear corner of the intake manifold just above the #4(I believe) cylinder spark plug recess. Naturally, the recess had antifreeze (along with some oil) in it almost to the top of the plug. The #7 and #8 recesses were also filled with oil, but no smell of antifreeze. Is there any way to remove the nipple from the intake manifold and reseal it without causing any damage? Or, maybe a way of resealing it without removing it(the nipple)? Or, is it time to replace the intake? Thanks again.

07-10-2010, 08:35 PM
If the leak is coming from the nipple where the hose hooks to, there is really no way to seal it. it is time to replace the intake. You may buy a little time by sealing it with a 2 part epoxy mixture. But the leak will continue to get worse. Sorry.

07-10-2010, 08:44 PM
I was afraid of that...........not because the job is too difficult, but because my dad is going to blow a gasket if he has to keep putting money into the car. You had mentioned something about having the right tools to do the job. Is there anything special that I will need? Also, would it be your opinion that the oil in the plug recesses is due to leaking valve cover gaskets?

07-10-2010, 10:18 PM
There is only the fuel line release tool that is not a common standard or metric tool. The oil may be from the valve covers. I would clean it really good and see where it is coming from. I think Dorman makes the intake with gaskets for somewhere between 2 and 3 hundred dollars. Good luck.

07-11-2010, 09:12 AM
Dorman makes good NPI intake manifolds with the aluminum coolant crossovers and gaskets built-in. The most common place to find these is on eBay (*F%3F&itemid=130403385374) right around $200. They are a direct fit.

You can also get a Ford Racing Performance Part PI intake manifold kit ( if you want to gain a little bit of torque and HP. It is not a direct replacement. You have to replace the coolant tube in the valley which requires the removal of the water pump, and using RTV at two corners of the coolant ports to prevent coolant leaking since the ports do not match up perfectly. Everyone I know who did this never had a problem with leaks after years of use. The kit includes everything you need for the swap.

Here's ( some good instructions for the Dorman NPI direct fit replacement

You only need basic tools for the job. I just bleed the fuel line pressure off by pulling the fuel pump fuse, turn the engine over a few times with the starter, and have a rag handy for the unpressurized fuel in the rail that comes out when you remove the fuel injectors.

Here's ( some pictures of my intake swap (with the PI swap kit).

You'll notice I had broken a bolt, too. That was my fault due to over torquing them and you shouldn't expect to have this problem.

07-11-2010, 11:33 AM
I do have a fuel line disconnect tool kit which is still brand new in the box...... have had it for about 5 years now. Found it for a great price back then and knew that I would need it some day. I started looking for intakes last night and saw the Dorman intake at several parts places. Where does one find the PI intake and how much do they cost? The valve covers have the appearance of being oil covered with years of dust in the oil film, indicative of the fact that the gaskets have been slowly seeping oil over a period of time. Thanks so much for all of the information; truly appreciated.
I will let you know how the job went once it has been completed.

07-11-2010, 12:19 PM

It's $300 from ADTR, a one man operation in California. I've bought most of my aftermarket parts from him and he's very helpful.

The instructions for the PI swap are here ( Only note is that instead of using the NPI gaskets, you will be supplied with the PI gaskets which only require RTV to be placed in the two coolant ports instead of the 8 intake ports. Most people who have done this go with the PI gaskets, including myself.

You don't even need to disconnect the fuel lines if you don't want to. I just left the fuel rail attached to the fuel lines and twisted it over to the passenger side of the engine compartment out of the way.

07-12-2010, 10:41 AM
What is the best method for removing the coolant from the spark plug recesses? The first time that I did it, for the #8 plug, I used a rag to get it down as far as I could, but there was still quite a bit that the rag wouldn't reach. So I piggy-backed a couple of Q-tips together and removed the remainder, but what a slow process that was. I just got a real good look at the source of the coolant leak........... the riser in the rear corner of the intake, where the metal nipple for the hose is inserted, has a 1 1/2" long crack in it extending vertically downward from the top. No repairing this one, even temporarily, so will be ordering a manifold today. Cheapest I've found is $206 and some change. Anybody know of a cheaper source?

07-12-2010, 01:56 PM
That sounds like the standard price of the Dorman intakes. You can go to a junkyard and find one for cheaper, but run the risk of the plastic already being weakened.

Get compressed air and blow the coolant out of there.

07-12-2010, 04:25 PM
Thanks for the compressed air suggestion (why didn't I think of that?!). Ok, I've got the old intake off, so now I've got some more questions. The interiors of the intake ports are covered with a sooty/crusty material........ looks like the same stuff that's in the throttle body in the area where the EGR ports are located. Does this indicate another problem going on? Should that crap be cleaned out of there, and if so, how do you go about doing so? Also, some of that debris has fallen down and is on the intake valves. Will this stuff blow out upon initial startup without damaging the valve seats, or should I blow it out with compressed air also? The Autoclinix instructions said to pull the fuel injectors up from their bosses while still leaving them attached to the fuel rail. Unfortunately, several came off of the fuel rail as they were pretty well stuck. Should I replace the upper o-rings on the injectors as well as the lower ones (I was already planning on replacing the lowers)? Also, 7 of the 8 locking tabs on the fuel injector electrical connectors broke off, I'm guessing due to heat fatigue. Is this going to create a problem where they start coming off during normal driving conditions? That's about all I can think of for now. All in all, the difficulty in performing this job is very minimal....... it kind of surprised me as to how easy it was. I'm more concerned with removing the valve covers as there doesn't appear to be much clearance(especially on the passenger side) and the wiring harnesses don't appear to have that much give. How does Ford number their cylinders? Is there an industry standard? I always though that you look into the engine compartment from the front of the engine, the left side(passenger) starts out 1,2,3,4 from front to back and then the right side continues 5,6,7,8 from front to back. Thanks again.

07-12-2010, 07:52 PM
You do not have to clean that black carbon out of there. That is from the EGR and oil that gets sucked through the PCV valve (you'll probably see a pool of oil in your old manifold). It will not damage the valves or valve seats.

I pulled the injectors completely off and replaced all of the o-rings, top and bottom. For the price, I'd rather do it once and forget. Remember to get some clean engine oil on the o-rings when installing them into the rail and manifold! They will tear if you do not.

All of my plastic retaining tabs broke on my injector connectors. I have had no problems after a year but if you want, zip ties will keep them attached securely.

Let me know how the vale covers go. I have to do that when I change my timing chain tensioners and install the PI cams.

07-13-2010, 08:26 AM
Just wondering if I should replace the coolant temperature sensor as long as it is easily accessible. It is mounted on the inboard side of the right head, tucked up under the intake manifold deck portion of the head and approximately 3-4 inches under the front of the intake manifold (when installed). Seems like it would be rather difficult to get to when it is all reassembled. Is it easy enough to do by just removing the alternator, or should I be doing it now? Why are you replacing your timing chain tensioners with such low miles on the vehicle? This car has 201k on it, and am now wondering if I should be doing the same. If I knew that I wasn't going to have a major issue with the exshaust manifold studs breaking off, I'd be pulling the heads off and replacing the head gaskets at this point (don't want to open up a bad can of worms!).

07-13-2010, 11:07 AM
That is the Cylinder Head Temperature (CHT) Sensor. The Engine Coolant Temperature (ECT) Sensor is located on the front of the intake manifold in the coolant crossover. The CHT can be easily removed by just removing the transmission if it is ever needed. I haven't seen one fail yet, though.

I am replacing my timing chain tensioners and arms because 2000-2003 model years used a cheap plastic on the tensioner arms and guides and they easily get worn through. If it goes too long it can lead to timing being jumped and a bunch of aluminum debris in the oil. Right now I'm just starting to hear the chains rub on the metal underneath the plastic so I want to get this taken care of this summer, and while I'm at it, I'm going to drop in the newer 2001+ PI cams which let the engine breathe better above 5k RPMs.

You can remove the heads without removing the exhaust manifolds. Just disconnect them at the cats and pull them off with the heads. Down side is clearance is even more of a concern now if you are pulling the heads with the engine in the car. I wish I had some help to pull my heads. My driver side gasket has a tiny leak of coolant into the valley and it's just annoying knowing it's there. I'd also port my heads and or get some Trick Flow Twisted Wedge heads. If you do pull your heads, give me a call. Maybe I can spend a day up in MI to help out.

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