DaveT

The inside groove measures .288" The outer thickness is .510" The flange on one side is about double the thickness of the other. Does this sound like the part you are looking for?

I found a couple, and a broken one. I will make a model and drawing so you can check the dimensions. They look like the thicker one, at first glance.

If you can get them, do yourself a favor and get stainless steel nuts and bolts. Flatwashers and lockwashers also. Studs for the heads to the y pipe. NOT bolts. Anti seize helps with all of this also.

That short pipe on the y pipe cat is a port for a carburetor heat riser. Just ignore it. It is not open to the exhaust. It allows warmed air from around the cat to be sucked into the carburetor via a lightweight flexible duct. Helps with warm up and preventing icing. Not applicable to SPFI.

I can try to locate the ones I have tonight. I could also print those now.

Is this engine a SPFI? or Carburetor? Most of what I've read in the thread leads me toward SPFI. Just want to be sure. I've seen many people use seafoam on these cars / engines with no negative effects, so I'm not thinking it's likely the cause. I have nothing to go on regarding Chevy engines, something could be different.

Check for ecu codes. If the o2 sensor is that bad, it should show a code. The CTS is also a common cause of weird idle changing idle. Depending on how it fails. It can be bad and not cause a code. Testing is best, as parts cost money.

Those things drive me nuts. If I ever have one that new, it would be on the list of modifications.

The axel stub on the side of the transmission moves around? That does not sound normal. I once bought a 1990 4wd wagon. . On the drive home, it was making a rythmic noise. Discovered there was no gear lube on the dipstick. Just black. Threw a quart of motor oil in it, as it was all I had, and got home. Changed it out to synthetic gear lube. Drove it for 11 years. The noise slowly faded. Just mentioned that because maybe that's the sound you are hearing.

I know first hand that for 4wd wagons. Spfi, 3AT automatic. 86 gl through 1990 loyale very similar parts for almost everything. Exhaust should be swappable. Minor differences crop up swapping between auto and stick, 2WD vs 4wd, stuff like that.

There should be aftermarket parts for it still. Might have to try looking them up as a 1990 loyale. They won't last nearly as long as the oem, but way lower cost. I built an all stainless exhaust - there's a link on another similar thread, but your not going to be doing that project in a parking lot.

I broke one up through the o2 sensor hole and the output pipe once. If you are good at welding thin metal, cutting an access hole would be easier. If you buy a new y pipe, no need to remove the catalytic. It won't make a difference in power.

There probably should be a spacer. Older and newer cars had them. There should be an inner and outer seal.

Something mat be partially blocking the exhaust, but it could be either of the catalytic converters also. The bolts on the exhaust are very likely so rusted that they need to be cut off with an angle grinder or burned off with a welding torch. Unless they were replaced with stainless, and or recently assembled with ano seize compound. Best to test before buying parts - loosen the nuts tat hold the y pipe to the heads, to get a gap between the flanges and the heads. Quarter to half inch. Be sure the studs are not backed out. If it runs and drives normally but loud, the exhaust is blocked. If it still runs badly, then the exhaust is not the problem.

Hp is mostly limited by the heads. Also the original carb. Exhaust is minor.

So the power at the fuses listed in post #25 is gone, as well as nothing in post #28? Have to start testing back toward the battery. Starting to sound like a corroded or broken connection.

If it is just a Y, it won't have a big bulge like there is for a cat or a resonator. I can't be specific about 84, as I skipped from a 78 to an 86 back in 1988. Never touched anything in between those years. Just the way it happened. Changing the exhaust will make it sound different, not much else.

Easiest test to check for blocked exhaust, is loosen the 4 y pipe to head nuts. Make sure the studs are not backed out. Get about a 1/2" gap between the head and the flanges. Take a drive. It will be loud. But if the exhaust is blocked, it will now have normal power.

That is a different reason. I never tried not resurfacing one. It might work for a while. But I'm not going to test it.

The jiggle pin hole is very small. Heat gets conducted and convection also. Kind of normal for it to get hot even before the thermostat opens. There is a small coolant hose on the bottom thermostat housing that allows some coolant to move while the thermostat is closed. The higher then lower temperature thing... Might be good to pull the thermostat and test it. A heat gun carefully - to not over cook it, or a pot on a stove top with water. Watch how it opens while the temperature rises. Should be smooth. The other thing I have seen cause that kind of warmer than normal then settle type thing, is when all the air wasn't purged. When ever I open the cooling system and partially drain it, I refill as much as possible, then idle until the thermostat opens, and make sure all the air is out. Rev the engine a few times , etc. one of those funnels that attach to the radiator cap and hold almost a quart of coolant help a lot. Don't do this purge by driving. The way the water pump is situated, it is possible for air to collect in the housing while the thermostat is closed, because low flow rate. Water pumps do not pump air well. When the pump stops pumping, the heads get over normal temperature. It may not be completely stopped, but much lower than normal, depending on how much air vs coolant. Eventually, the heat makes it to the thermostat and it opens. Water shifts, etc. pump catches enough, and coolant flows, pushing the air out. The air is no separated in the radiator, but the heads have been overheated a bit.

When cold. Sharply squeeze the upper hose. If there is air, you will hear it gurgle, in addition to the giggle pin. Its ok if there is a little air. The real thing to watch for is change in the amount. Increasing is not good. Also, this will let you catch it hopefully before an over normal temperature while low on coolant situation. Sometimes I have seen the recovery tank stay in its normal range, but way too much air in the system.

Would the drums be usable (in spec.) if they were turned? The shoes on my 76 and 78 4wd wagons were the same overall size and shape as those on my 86 GL through 93 Loyale. There were some differences in holes as the newer cars had auto adjusters. Might be worth taking a look at a pair of those if you are having trouble finding shoes for 78.

Power goes to the ignition switch on a fat white wire. Power to the engine & ECU etc. is a Black wire. Should only be 12V when ignition is in run and start positions. It goes to the 3 fuses for: Meter Engine IG-COIL FUEL ECC Back Turn 4WD AT Those should all have 12V with the key in run & start positions.

Yes, the gasket just to the right of the water pump is a head gasket. The slow seep may also let in air. It will slowly get worse over time. It may also have started from running over normal temperature while low on coolant - which also eventually causes the head gasket to fail allowing combustion gasses into the cooling system. Time will tell. Just keep a close watch on the coolant levels and air quantity in the upper hose.

Wrist pin plugs open to the crank case, not a coolant passage.