well, today the cooling system was flushed and a new rad cap added. Noticed the water pump is brand new from previous owner. Did the engine 'block test' with a buddy who has a clue - it failed.

I ordered the haynes manual and will be researching here a whole lot more before going further. I don't want to go to the trouble of replacing the head gasket, getting the head machined (or new head) if there could be other major problems lurking.

fun fun

question now is - is it safe to drive at all ? no visible mixing fluids. If I prevent overheat is it safe to drive or should I just park it until I get this worked out ?

cheers

 

What kind of block test failed?

 

a compression test?

 

pretty much the same as this thing http://www.blockchek.com/

got it at napa

 

That's a good one assuming the cooling system is free from all air(bleed system) and all seals(thermostat,water pump,radiator,intake manifold) and hoses are in proper condition.

Just saying......I've seen them give wrong results.

 

Start with a compression test on all cylinders. The compression spec for the 4.0 is 120-150 psi, with no more than a 30 psi variation between cylinders.

 

Ok... a compression check I can get done next week when my usual shop opens. But someone else mentioned a leak test. I've never even heard of that one to be honest. How is it better/different? Which should I get done ? Obviously I'm not wanting to spend too much cash lol

 

Ouch So not your first choice

 

I used a kit from Autozone & it was positive so I go thinking I have a bad head or gasket & it turned out all I needed was a radiator, TS, water pump ect.....

People will also tell you there is NO WAY a head gasket can "leak oil' but my RENIX 4.0 does. There is a reason why but I won't go into that now other than to say there is a passage there for oil seepage usually right above where the dizzy cap is.

 

A compression test is simpler and will cost you less. A leakdown test is more comprehensive and can often tell you more, but will cost a bit more.

I generally start with a compression test as it only takes a half hour and it often tells the story. But your call. Ask the technician at your shop for their opinion.

 

My 88 was over heating, after reading all i could here this is what i did.....
new thermostat, new radiator, new water pump, new res bottle n cap. new hoses.
make SURE YOU BLEED THE AIR OUT OF THE BLOCK!!!!!!
one trick is to jack up the rear end of the truck.
never got hot again.