I've noticed recently that my 3.4 has been leaking some coolant. The water pump was replaced about 20 000 km ago and hasnt had any issues yet. The coolant seems to be leaking from behind the water pump on the left hand side. The picture isn't mine but the leak is in the exact same place. I have done some research and it seems that it could possibly be the timing cover. Just wondering if anybody has had any similar issues?

The other problem I am having is leak from the rad cap. If I go for a relatively short drive, less than 30km or so and don't push the car at all the problem doesn't seem to occur, but on trips greater than about 30km and pushing the car a little it is very noticeable. After the longer trips, I open the hood and the entire rad cap area is covered in coolant and steaming. The coolant is being pushed out of the rad cap, I replaced the rad cap and the problem is still occurring. There is no white smoke in my exhaust and my oil is not milky at all but I was wondering if this could still be a head gasket issue? Has anybody had any experience with this at all?

Thanks for any input.

Also forgot to add that the car does not overheat at all.

 

the pic looks like a timing cover gasket... and as for the cap you may need to replace the rad get a coolant pressure tester and pump the system to 16lbs (7kg i believe) and check to see if the rad is cracked at the cap

 

If it's not the timing cover, there's a nipple that goes into your intake manifold with a pipe coming out of it. It could be leaking from the pipe if it's really rusty or it could be leaking from the threads of the nipple. I just fixed this problem on mine. Teflon didn't work that great on the threads, leaked after a week. Instead I used some gasket sealer. RTV, permatex, anything will work as far as I know.

 

So I just pressure tested the rad, and the rad isn't cracked and the cap is perfectly fine. Any other ideas as to what it could be?

 

the hose that goes from the radiator to the overflow tank may be cracked, or missing.

 

Yeah, sure could be the timing cover-to-block gasket. The gasket is pretty narrow in that area and the timing cover will expand more than the block when it heats up. That means lots of relative movement between the block and the cover which will compromise the gasket eventually. See the pics of my 3.4 during teardown and buildup below.

Be sure that the coolant isn't coming from above though. The timing cover at that area has a cavity that collects oil, coolant, dirt, or whatever from above. It could very well be that stinkin' quick connect fitting for coolant at the very front of the intake manifold. It's very problematic. Could bt the thermostat housing. Could be the heater pipe connection at the pump or even the throttle body heater hoses.

 

Alright so there is still a small amount of coolant leaking out of the rad cap, but only after I drive the car decently hard. When trying to determine the coolant leak, me and my dad found an intake manifold gasket leak. I've purchased the gaskets and were going to replace them this weekend. Anyone have any other ideas about what could be causing coolant to leak from the rad cap?

 

the only thing i can think of is that your getting air in the cooling system through the intake leak, or failing head gasket. air will cause a steam buildup that can boil over, overwelming the system and releasing out the cap. hopefully once the gasket is replaced the problem will be no more.

 

You're going to R&R the *lower* intake this weekend? I hope that you and/or your dad are pretty experienced DIYers because that is *not* a trivial job. The lack of space above the engine makes it a pretty miserable experience.

You have to first pull the fuel rail and injectors, then the upper intake.

Valve covers have to come off.

Only then is it lower intake time and watch for the two different length bolts plus 4 locations with studs/nuts. The *orientation* of each of the washers is important so pay attention to the way the fasteners come out. The washers are cupped and face each other to act as springs. Don't lose any.

The pushrods go through the lower intake gaskets so, technically, you should loosen the rocker adjusting nuts enough to remove the pushrods. You'll see the new gasket marked "DO NOT CUT" and now you know why.

Upon lower intake reinstallation you *must* put a dab of silicone sealer at each corner. also a bead at the front and rear edges.

I assume that you have a GM factory or Haynes manual. If not, get one now.

The job is doable at home for sure but take digital pics, make notes, tag parts with masking tape, etc. to leave a trail of breadcrumbs.

You'll need a 3/8" torque wrench too.

Good luck!

 

My dad used to run/manage a mechanics shop so he has the knowledge, and I figured it would be a lengthy job which is why we set the entire day aside tomorrow to do the job. Thanks for the additional input though, I'll definitely use the advice. I'll make a follow up post once we finish to see if the coolant is still leaking.