1995 3800 losing coolant

My Trans sport 3800 1995 is loosing coolant. It has been a slightly leakage at the intake manifold gasket för the last years. (about 1 litre every 1000-2000 miles). The leakage has increased drasticly the last month. I am about to change the intake manifold gaskets, but how to tell if also the upper intake manifold or even the head gaskets have to be repaced?

As long as there is no oddity with the heat supply from the heater or erratic engine temperature, I would consider the head gaskets are OK on cylinder side..which does not mean they could not leak coolant outside...but the stress on that side is minimal, hence, a low probability, and this would leave traces outside .
And the upper section of intake manifold has no coolant passage.
BY hte way, my '93 3.8 has taken some coolant for years, really a little, may be half as you said , ....no idea from where, never any trace, did not investigate.

As long as there is no oddity with the heat supply from the heater or erratic engine temperature, I would consider the head gaskets are OK on cylinder side..which does not mean they could not leak coolant outside...but the stress on that side is minimal, hence, a low probability, and this would leave traces outside .
And the upper section of intake manifold has no coolant passage.
BY hte way, my '93 3.8 has taken some coolant for years, really a little, may be half as you said , ....no idea from where, never any trace, did not investigate.

OK, so there is a difference with the series II engine? What I have read, that engine has problem with corroded plastic upper intake manifold, for example, see: http://cgi.ebay.com/ebaymotors/Upper-Intake-Manifold-Plenum-GM-3800-1996-2005-3-8-V-6_W0QQitemZ130212445425QQcmdZViewItem?_trksid=p328 6.m20.l1116

I have in the past sometimes seen a little water passing out in at the intake manifold gasket, but as long as it only took a little coolant, I just ignored it. Now it takes about 1 litre every 10 miles! Heatsupply is working just fine. Engine temperature goes up and down between 83 and 87 degree C (hysteresis of the thermostate?). Most of the time stable at 84 degree C. At some times, with too little coolant in the system, the temperature have gone a bit higher, but never above 100 degree C. Could the intake gasket leak coolant both into the engine and out?

yes..the series 2 , not used with the TS, (but Tom Van Hooft is changing that) is known for problems with the upper intake...
http://www.bonnevilleclub.com/forum/kb.php?mode=article&k=38
http://www.automotiveforums.com/vbulletin/showthread.php?t=401247
..but wow, it's taking as much coolant as fuel.....at such a rate, if it were head gasket, it would surely generate bubbles out of the radiator at idle.....
..and the slight variation like 83-87 is typical of mine too...but have not experienced low coolant levels to 100.
I have used low pressure (like 15-25 psi 1 to 2 bar) compressed air applied to spark plug holes to test for air coming out as bubbles from the radiator. I just hadto position the piston on compression top dead center and with a blown head gasket, air would show right away at the radiator ( filled to the top) . My late DOdge Omni was hard on head gaskets....
I would think physically possible intake gasket to leak inside and out..but no hands on experience ..

With that rate of coolant leak, if it it were going internally, your dipstick would be registering very high as well and looking a very sickly brown color. The intake manifold on my 95 3800 was leaking about a year ago, and I changed all gaskets, including upper plenum and throttle body gasket. You may not have to change all of them. The leak showed up at the front drivers side, around the vincinity of the thermostat and EGR, the valley there will always be wet. Just as an aside,the manual says to leave the upper and lower manifolds together unless you are replacing parts, but after a day and a half of struggling, I gave up before something expensive got broken and pulled the upper plemum off. I just didn't find any room to work, and 2 hours later all is apart. Good luck
Jeff

..but wow, it's taking as much coolant as fuel.....

Maybe not that much, but I have to fill it up with coolant at least twice a week. I have not seen any coolant at the front of the engine, and I can´t access the back side. I have notice some white smoke from the exhaust, especially at start, but I is hard to say if it is normal or not as we have around 0 degree C here now.

Is there any risk with higher pressure, checking the head gasket? With radiator cap off, there could not be any pressure in the radiator?

Is there any risk with higher pressure, checking the head gasket? With radiator cap off, there could not be any pressure in the radiator?
..in fact what I had was a rather small compressor with no tank....so it could not and would not have time to develop large pressure before a leak could be detected. Leaks would show rather soon without not much pressure. ANd for a piston with no leak on which you would insist keeping the pressure on, pressure would increase and if piston is not perfercly at TDC, pressure would just act on it and rotate the engine....so that is why high pressure is neither necessary and can even be a nuisance.

..And I am always skeptical on the "white smoke" syndrome, as indeed low outside temperatures will do that at startup, and once engine it warmed up, the added coolant leak will vaporize invisible as much as the water from combustion products. But if some water accumulates in a cylinder, yes it will add lots of white smoke at startup, but absence of it if not a sign of no leak. My Omni would drink lots of coolant, no smoke, no increase in oil level, but lots of gargle in the heating system, and overheat. Means it takes the coolant only when the engine runs and then vacuum exploits gasket leaks on the intake stroke, and then compression and explosion strokes push air and exhaust back into the cooling system ...

[QUOTE=LMP]..in fact what I had was a rather small compressor with no tank....QUOTE]

I have a very small compressor that I use for inflating tires, for bicycles but also cars. I guess the capacity is about the same as the TS build in compressor. Is this compressor enough, or can I use air from a spare wheel?

I do not see any bubbles in the radiator at idle.

I have a very small compressor that I use for inflating tires, for bicycles but also cars. I guess the capacity is about the same as the TS build in compressor. Is this compressor enough, or can I use air from a spare wheel?
All of that is perfectly suitable.


EDIT: reference to Jeffrv's input below
http://www.automotiveforums.com/vbulletin/showthread.php?t=771790

Another possibility on that engine is the nipple on the intake maifold, located under the alternator. from the factory it was a plastic threaded nipple, very prone to cracks and leaks, this may explain the sudden increase in coolant loss. Replacement nipples made of metal, don't have a problem with them.
Jeff

Another possibility on that engine is the nipple on the intake maifold, located under the alternator. from the factory it was a plastic threaded nipple, very prone to cracks and leaks, this may explain the sudden increase in coolant loss. Replacement nipples made of metal, don't have a problem with them.
Jeff

Right on spot! I just checked for leaks with the engine at idle once more and found dripping coolant from that nipple!

I have noe replaced the nipple. It looks like the head gaskets are OK, even though I did drive the car allmost without ay coolant the last time!

The local GM dealer did charge 300 SEK, about 50 dollar for a new nipple! I thought that was fair to much, and made a new one out of parts in my "plumbing kit". The nipple has a regular 3/4" pipe thread, and the hose is 15 mm.