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"WTF do I do now" THE SAGA CONTINUES

Thanks to all for the thoughts. This is a 1988 Blazer btw.

I do not understand what the coolant pressure test will tell me. I already have coolant dripping out of my catalytic. If I pressurize the coolant system won't it just start coming out of the cat again ?

How will this tell me that it is the head gaskets vs the block ?

Should I just pull the heads to check ?
 
I'm sure you could pop the heads off and likely see where the gasket is bad, if that is the issue.

However, once you pull the head, if there is a small crack, you may not see it. I've not had to deal with it, but I knew a guy who had a block magnafluxed, and only after reassembly was the crack in a bore noticed.

By pressure testing the system, if there is a leak, and it is on one side/specific cylinders, you will KNOW where to look for the leaks when the heads are off. That way, if the head is pulled and you don't see a bad gasket, you know something else is going on.

That's my thought process anyway.
 
Are you saying I should remove the heads, if the gaskets are blown then I should assume that is the problem.

If the gaskets are fine then there is a crack somewhere else and I should replace the engine ?????
 
No, I'm saying pressure test it before you pull anything apart.

If a cylinder or cylinders fill with coolant with a pressure test, pay close attention to those when you pull the head(s). If the gasket is obviously bad, you know you found the problem. If the gasket does not show evidence of failure, pay attention to the chamber and cylinder(s) that filled with coolant. This is just insurance that you don't pull the heads, can't find where a gasket failed, throw it back together, and still have the problem.

If a head crack, no reason to replace the block IMO.
 
Hi, I know this is my first post but bear with me. I will do a into later. 6.5 blocks are known to have coolant issues and when looking for them they are not always obvious. you need to be a bit of a detective and be methodical. first start with the pressure test as was previously mentioned. build up pressure with a good tester. note many tester pumps will slowly bleed down given time so this is not always a indication of a leak just the body of the pump leaking a little. Put a sheet of clean cardboard under the truck. this will help to identify any external leaks and where in the engine compartment you need to look. Eliminate any external leaks like a loose hose clamp or weeping from the water pump vent hole. If you determine the truck is consuming coolant through the engine and you decide to pull the heads do this carefully. Have a friend help you when you lift off the heads so you don't smash up the old head gaskets. you will want to very carefully inspect the head gaskets for any sign of problem. ie improper gasket location, improper head torque {example the gasket does not look like it is compressed properly around the coolant passages} of damage to the gasket because the previous tech damaged them on install last time. this happen a lot when placing the heads on the block as they are very heavy.

If the gaskets look ok start looking at the undersides of the head for cracks in the combustion chamber area to the coolant passages. These cracks can be very small and hard to see but still cause a lot of trouble. The heads and the head gaskets are usually the problem.

It is possible that you don't find a problem yet. Put a socket on the crank to rotate the motor and inspect each cylinder wall with a small inspection mirror and a good light. you are looking for a fine vertical crack in the cylinder wall. these can be very hard to see. As the engine heats up and the coolant pressure build the crack in the cylinder wall slowly expands and will feed coolant into the engine. look for pistons that don't have soot or carbon build up both in the engine and on the head. the hot coolant acts a a steam cleaner this may help to find the problem hole. I have found the two rear most pistons are most common for this #'s 7 and 8.

@dyeager535 is correct that some time the crack is so small only magnifluxing the block will find them. If you are new to this type of diag don't expect to have something jump out at you as the obvious problem. you have to look carefully.

Good luck, look at this project as a good way to get to know your truck and how it really works. don't be afraid to jump in and try it your self. There is a lot of good knowledge on this board, ask a lot of questions, use your common sense and you will be fine.
Kirk
 
vintagerodshop said:
6.5 blocks are known to have coolant issues and when looking for them they are not always obvious.
Click to expand...

Don't discredit the rest of this post, as it was a well thought out, and still applicable information, but isn't this a 350?

Martin
 
Yes this is a 350 tbi.

I feel the problem is beyond my ability at this point. I found a retired mechanic here in Las Vegas, who therefore has no vested interest in selling me an engine, to check out the problem.

He does this in his spare time so I have to be patient. So far he tells me that the engine failed the coolant pressure test. He removed the plugs and found fluid in one of the cylinders.

He is thinking about the problem and will let me know. I have other vehicles so I can be patient. I will report back when I know something more.

BTW. I met a mechanic from KSD (Kreative Street Designz). He does LS swaps. Anyway he tells me that this engine can also have warped intake manifolds. Often when heads are worked on no one checks the intake for flatness or if they do they just over torque them down anyway. I do not really understand the effects of this but he says that this could be the cause of the leakage into the cylinders as well and it is important when working on the heads to thoroughly clean the intake and inspect it for flatness. Also he recommends that high performance gaskets be used when reassembling.

Finally he said that the 350 can trap air in the coolant system after draining the coolant. He puts a soda bottle with the bottom cut off in the radiator opening. Fills that with coolant and burps ,aka squeeze, release squeeze etc, the lower hose until the only effect is of the coolant going up and down in the bottle. Of course when air comes out, the coolant in the bottle enters the system and has to be refilled. Just wanted to share that one. :waytogo:

Thanks to all for your help and ideas. I will get back to you soon.

Regards to all,

Tom
 
Uh, you may want to do a search on kreative. I recall negative stuff last time I was scanning around looking for bailing wire and duct tape as a means to remedy my blinker fluid leak!
 
chevyfumes said:
Uh, you may want to do a search on kreative. I recall negative stuff last time I was scanning around looking for bailing wire and duct tape as a means to remedy my blinker fluid leak!
Click to expand...

Glad you caught that too.

Check in with muddysub's thread and you'll see some experience of their work by another member. It's not good.
 
I do what I can.... And if that means stirring the pot. Well I guess, if I have to, if my arm is twisted enough....:D let's hope we caught it in time before the spodededed happens.
 
When I drain the coolant in my engines I've always filled to the top, start it up and keep filling as it warms up. Upper hose will get warm, and then probably draw it down again as it fills the empty spaces in the block. After a few mins of that the coolant starts to get hot and expands and then I cap it.

Then I'll go back later after it's cooled and do that again - and maybe a 3rd time as it works the air pockets out.

If you have coolant in one cylinder you either have a crack in the head, or the block or a head gasket leak. Its slightly possible an intake gasket could do that but unlikely. and it would either be cyl 1/2/7/8 as they are the only ones next to the coolant passages where the intake is.

Josh
 
The blocks are canted upwards towards the front, "burping" the block should only be necessary on vehicles (modern) that have the radiator cap lower in the system than the engine. Air goes to the highest point, which is the cap on our trucks, which is then expelled out through the overflow bottle as the coolant heats up and expands. When the fluid cools, only liquid is pulled back from the reservoir (which is why the reservoir has a minimum line) because the intake is at the bottom.

Theoretically, as long as you keep adding fluid to the overflow, and there is SOME fluid in the radiator, you never have to open the cap. It's just a faster way to get it near full.
 
That should be true. But I like to go over mine again. I'm a belt and suspenders kind of guy... lol

:D
 
If it's not true, something isn't working right! :)

Cap failure does happen, proper function of the radiator cap is crucial. Not really thought of, until it fails.
 
82355 said:
Don't discredit the rest of this post, as it was a well thought out, and still applicable information, but isn't this a 350?

Martin
Click to expand...

I think that post was directed towards me and my 6.5TD story. Thanks to vintagerodshop for sharing! I will keep that in mind. :bow:
 
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