problem with HOT engine

"sq1euo" skrev i melding news:f1dq94$q4k$ snipped-for-privacy@achot.icm.edu.pl...

1. Mixture too lean
2. Ignition too late
3. Thermostat bad (or incorrect replaced)
4. Air in the coolant system

Could be something else, but... try the 4 above first.

I would definitely check the coolant temp sensor, I've come across a couple of bad ones lately, one I got off a straight 740 in a junkyard, makes me think that's probably why the car ended up there in the first place. Apparently it will cause this symptom if it goes open circuit.

U¿ytkownik "James Sweet" napisa³ w wiadomo¶ci news:Bp3%h.3176$XG1.1923@trndny07...

I've think the same

10 deeg.

new one

new liquid,..without air

-- Jarek (SQ1EUO) - V740 1988, B200K + LPG snipped-for-privacy@stud.pam.szczecin.pl GG:1277234

U¿ytkownik "James Sweet" napisa³ w wiadomo¶ci news:Bp3%h.3176$XG1.1923@trndny07...

I think the cooland sensor is OK,....but anyway car goes wrong and engine run bad, The alle cooland system is new (radiator,theromstat, coolant liquid).

-- Jarek (SQ1EUO) - V740 1988, B200K + LPG snipped-for-privacy@stud.pam.szczecin.pl GG:1277234

Since the cooling system was rebuilt, I would suspect an airlock or air bubble in the cooling system. Have the mechanic that did the work check.

But he said it's running poorly when hot, surely if a cooling system problem were to blame, it would have to be hot enough that some major damage is being done for it to start running poorly.

[ ... ]

Or a coolant sensor is losing contact with the coolant when the thermostat opens.

I'd double check that the radiator is full, not just the overflow reservoir.

Gary

U¿ytkownik "Gary Heston" napisa³ w wiadomo¶ci news: snipped-for-privacy@corp.supernews.com...

I've checked it. Cooling system is 100% OK.

-- Jarek (SQ1EUO) - V740 1988, B200K + LPG snipped-for-privacy@stud.pam.szczecin.pl GG:1277234

Jarek, if I understand correctly it overheats in traffic jams but is okay when you get out on open road? If so, the air flow is probably the problem.

You probably have a fan on the water pump that is driven by a finned aluminum "viscous coupler." If that coupler has lost some of the silicone fluid it will be too weak to cool the radiator when the car is at low speed. You can check it by trying to spin the fan by hand with the engine off. If the fan stops within a quarter turn the coupler is working okay, but if it goes more than 1/2 turn it is bad. Between 1/4 and 1/2 turn it is not very good, but it is not the cause of your overheating.

I think there is also an electric fan on the front of the radiator; that should be running when the engine gets hot (or maybe with the air conditioning on - I forget which or both).

Mike

Uzytkownik "Roadie" napisal w wiadomosci :

I check "in" hose - it's full on liquid. The radiator have special little hose to take off the air bubble,...it is in highest place of the radiator.

-- Jarek (SQ1EUO) - V740 1988, B200K + LPG snipped-for-privacy@stud.pam.szczecin.pl GG:1277234

U¿ytkownik "Michael Pardee" napisa³ w wiadomo¶ci :

No...on open road is also bad,.,...but in trafic jam is horrible.

Visco is new, it's 100% OK,...the radiator is't hot in trafic jam,because visco works good. The radiator is also new.

I haven't got electric fan in my car,..only visco, rear radiator. It's look like only up part of the engine, the engine's head is only too hot,..but the block, sensor etc. is OK,..good temp.

Can I check the mixture by multimetr and lambda sond ???,...I've got old lambda sond in my out manifold,..because manifold is from injection engine.

-- Jarek (SQ1EUO) - V740 1988, B200K + LPG snipped-for-privacy@stud.pam.szczecin.pl GG:1277234

Is the cooling system holding pressure? I've seen a cracked expansion tank cause overheating.

U¿ytkownik "James Sweet" napisa³ w wiadomo¶ci news:pYp%h.490$dj2.277@trndny02...

Yes,the pressure is OK,..I've chacked it

-- Jarek (SQ1EUO) - V740 1988, B200K + LPG snipped-for-privacy@stud.pam.szczecin.pl GG:1277234

The radiator is not hot when the cylinder head is hot? Maybe the thermostat was put in upside down? It is not hard to make that mistake. That prevents the thermostat from working right so the hot water can't leave the head. If it's a genuine Volvo thermostat it has a little hole that will let a little water through, but just enough to let the head temperature get to the thermostat when the engine has been cold.

U¿ytkownik "Michael Pardee" napisa³ w wiadomo¶ci :

No it's 100% OK.

Thermostat is new one also,...88 degr.

-- Jarek (SQ1EUO) - V740 1988, B200K + LPG snipped-for-privacy@stud.pam.szczecin.pl GG:1277234

"sq1euo" skrev i melding news:f1pmft$f8r$ snipped-for-privacy@achot.icm.edu.pl...

If the cylinder head gets extremly hot, it seems to be a problem with either ignition timing or mixture. Check the color of the spark plugs. Run the car for a few minutes until the enginge gets hot. Then unscrew one spark plug and check the color and how the spark plug looks.(Be careful! It's very hot!!!) If you have a Haynes manual for the car, you can find a color chart for spark plugs on one of the last pages in the book. Or try to find it on the Internet.

Or this one (for MC's but ok):

or this one: This may tell you something about the mixture. Black - Too rich White - Too lean chocolate/grey - ok Broken ceramic around the core - too hot (lean mixture)

Theese are the basics.

Is the water pump ok? I got a rock in mine once from a junkyard radiator, it jammed the impeller which just spun on the shaft so things looked fine from the outside but no water was being pumped.

In article , Knut Solem wrote: [ ... ]

If the head was that hot from a mixture/timing issue, the incandescent glow from the exhaust manifold and turbo would give it away.

Coolant isn't flowing for some reason; if it's not a reversed thermostat, or failed pump as someone else mentioned, it could be a weak lower radiator hose collapsing under suction. Check by squeezing the hose from under the car; if you can get it nearly flat with your hand, it needs replacing. It may be possible to spot this by watching the lower hose while reving the engine; if it deforms at all, it's bad.

Yikes! No! Never try to remove a spark plug while the head is hot; there is a high probability of damaging the threads in the head. If that happens, the cheap fix is a Helicoil; the expensive fix is a new head.

[ ... ]

That color chart applies when the plugs are cold, not hot.

Gary