I just went through a bit of a mess trying to figure out why my Opel was overheating. Here it is for anyone that has similar problems:
Symptoms and steps:
Original engine ran but had only 60 lbs compression in #4 cylinder - rest had 140+. Wet testing #4 did not improve the compression and valve train was checked while running and appeared to be functioning correctly. Re-adjusted anyhow and tried again. No improovement. Also no prefire or backfire. Never ran this engine long enough to get very hot. Assumed the head or valves were damaged/worn.
Replaced with rebuilt engine. Water temp climbed nicely to 180 and then just kept going - leveled at 280+. so...
Checked timing (on the mark), carb (a bit rich and definitely not lean), Radiator (full and no leaks), and verified all hoses were good (all are new).
Removed thermostat and ran without. Same result.
Spit on water outlet (my personal version of a guage check) and spit danced like it was in the skillet! Guage was correct if not low.
Crapped my pants (now Im wondering how many minutes I have run this thing this hot and whether the head is damaged).
Checked water pump. Seemed to flow OK but replaced it anyway - visible electrolosys in return passage.(second clue) Ran again with new pump and no thermostat. Same problem.
Removed pump and used a coathanger and high pressure hose to see if there was junk in the head or block. No garbage came out and the engine seemed very clean.
removed both radiator hoses and ran water from top to bottom. Water flowed through with a small delay. Hmmmm.... not blocked but I wonder what it means to be 'blocked'? How fast should the water take to pass from top to bottom?
Took radiator to friend that does custom radiator work. He flow tested it (fancy way of saying he ran water through it under pressure). Water weent through but --- he said it was blocked. Turns out that water should flow through with almost no resistance. Anything else is considerred blocked.
Recored the radiator with a nice high efficency 3 row, and had a petcock installed ($230 or so for the job at Jerry Young Radiator in LA). He saved the old core so I could see the 'blockage'. The rods were passable, but clearly had a lot of buildup in them. Too bad you cant see this due to the way the filler is set off on an ear.
Replaced and ran (without thermostat). Temp would not reach operating temp. Replaced thermostat with new 160 degree (dont trust old thermostats and I live in a warm climate). Runs perfect.
So the lesson is: Blocked isnt really 'blocked'. If the radiator flows slowly it is blocked. Water should run through with no noticable restriction. AND dont run plain water in your car - most of the junk was clearly calcification and the pitting in the pump and thermostat housing was also from running water without additives. I ended up replacing the thermostat housing as well because of severe pitting.
I run my cars with 1/4 coolant, 3/4 distilled water, and Water Wetter (1/2 pint for an opel).
BTW: I got lucky and dont have any head damage. But I bet the original engine does. Too bad, the internals look as if it was rebuilt last week.
Symptoms and steps:
Original engine ran but had only 60 lbs compression in #4 cylinder - rest had 140+. Wet testing #4 did not improve the compression and valve train was checked while running and appeared to be functioning correctly. Re-adjusted anyhow and tried again. No improovement. Also no prefire or backfire. Never ran this engine long enough to get very hot. Assumed the head or valves were damaged/worn.
Replaced with rebuilt engine. Water temp climbed nicely to 180 and then just kept going - leveled at 280+. so...
Checked timing (on the mark), carb (a bit rich and definitely not lean), Radiator (full and no leaks), and verified all hoses were good (all are new).
Removed thermostat and ran without. Same result.
Spit on water outlet (my personal version of a guage check) and spit danced like it was in the skillet! Guage was correct if not low.
Crapped my pants (now Im wondering how many minutes I have run this thing this hot and whether the head is damaged).
Checked water pump. Seemed to flow OK but replaced it anyway - visible electrolosys in return passage.(second clue) Ran again with new pump and no thermostat. Same problem.
Removed pump and used a coathanger and high pressure hose to see if there was junk in the head or block. No garbage came out and the engine seemed very clean.
removed both radiator hoses and ran water from top to bottom. Water flowed through with a small delay. Hmmmm.... not blocked but I wonder what it means to be 'blocked'? How fast should the water take to pass from top to bottom?
Took radiator to friend that does custom radiator work. He flow tested it (fancy way of saying he ran water through it under pressure). Water weent through but --- he said it was blocked. Turns out that water should flow through with almost no resistance. Anything else is considerred blocked.
Recored the radiator with a nice high efficency 3 row, and had a petcock installed ($230 or so for the job at Jerry Young Radiator in LA). He saved the old core so I could see the 'blockage'. The rods were passable, but clearly had a lot of buildup in them. Too bad you cant see this due to the way the filler is set off on an ear.
Replaced and ran (without thermostat). Temp would not reach operating temp. Replaced thermostat with new 160 degree (dont trust old thermostats and I live in a warm climate). Runs perfect.
So the lesson is: Blocked isnt really 'blocked'. If the radiator flows slowly it is blocked. Water should run through with no noticable restriction. AND dont run plain water in your car - most of the junk was clearly calcification and the pitting in the pump and thermostat housing was also from running water without additives. I ended up replacing the thermostat housing as well because of severe pitting.
I run my cars with 1/4 coolant, 3/4 distilled water, and Water Wetter (1/2 pint for an opel).
BTW: I got lucky and dont have any head damage. But I bet the original engine does. Too bad, the internals look as if it was rebuilt last week.