Here is a pic of my LIM upside down. The shop that replaced the LIM said the leak was from corrosion in the manifold but I don't think so. there is a ~10" long, 1/4" thick bead of RTV sealant laid between the intake and the block.. I believe this is where my leak was. Over time hot water must have broken through a gasket, entered the chamber and pit a crack through the original sealant. Then one day more sealant gave way and the engine rapidly overheated.

 

1. There are coolant leaks l see on the pavement under the truck around the perimeter of the engine. Does this indicate that it could or could not be the LIM gasket or the head gasket?

2. Do you have a picture of the water passages to engine?

 

1. not necessarily.
2.) Read Christine;s post and look at his diagram

 

The leak was from a hose that connects to the something near the air intake. It was under other stuff where I couldn’t see it, near the center of the top of the engine.

 

Was this hose pretty short with a sharp bend to it? If tes, it would be the water pump bypass hose. This hose allows coolant to bypass the thermostat so that there is always some coolant flowing.

So was the leak in the hose or were you able to stop the leak by tightening the hose clamp?

 

The leak was stopped by replacing the clamp. The leak stopped for a few short trips for a few days. Now the leak is back.

Thank you for help. Now I’m going to another mechanic. They don’t know until they see it. Advance auto parts and Napa auto parts don’t know name of the hose. The goes from the radiator to something I don’t know the name of I don’t know if it goes to the heater core. Does the water pump bypass hose go from the radiator to the intake manifold?

 

Here are some exploded diagrams that might help. Using these, can you identify which end of which hose had the leak?

This first one shows the heater hoses and how they connect to the water pump (hose #2) and the top of the intake manifold (hose #6).





The next picture shows the remaining hoses, highlighted in pink. Hose 21 is the water pump inlet or "bypass" hose.

 

The leak is where the larger hose at the top of the radiator connects to a smaller hose that goes to something I don’t know what is. I think it goes to the engine. It could be the lower intake manifold that it goes to.
Can it cause damage to the hoses when you do a coolant pressure test that connects to the radiator cap?

 

OK, I'm not following the description of where your leak is. The upper radiator hose connects to the engine at the thermostat housing. Perhaps you could download one of the pictures I posted and mark where the leak is?

As for any possible damage a coolant pressure test could do, as long as you only pressurize the system to same pressure as the release pressure of the radiator cap, about 14 p.s.i. no damage will occur as long as the components are fine. If you do see a leak or if a hose starts to leak, then you would want to replace that part anyway since the cooling system is intended to operate at 14 p.s.i. as determined by the radiator cap rating.

 

98 Blazer 4dr 4wd
Which components that were already damaged can be worsened by the radiator pressure test? The leak is where the short black hose with 90 degree bend connects to the other hose that goes to the top of the radiator in the photo in the link below. The connection is underneath the air intake.

4.3 Liter OHV 12-Valve V6 Engine for the 1998 Chevrolet Blazer #52202305 | GTCarLot.com