Get the latest advice about your car

Get Started
Advice » Q&A » 1994 Buick LeSabre

Q&A

Ask Your Question

1994 Buick LeSabre

Question: cars runs good, but exhaust manifolds get cherry red block is much cooler

Question

Visitor, Laurens, SC, May 08, 2011, 20:06

I have a 3800 v6 we have done a compression test all cylinders are at 150 psi. cooling system pressure check holds 18lb. no oil in coolent or coolent in oil. engine runs smooth, and starts easy. Runs well and not overheating running at normal temp. cooling fans working. How ever the exhaust manifolds get very hot. much hotter then the engine and when you hold the gas to about 2000rpm they turn cherry red. starts close to the heads and moves down the exhaust. Any one ever have this problem?

2 Answers
Answer It
Flag This

  • Answer #1

    patrick mannion from Greg Solow's Engine Room, May 08, 2011, 20:51
    Profile_thumbnail
     Master

    The exhaust manifold does get very hot but if it is glowing cherry red it could be a restriction in the exhaust/ restricted catalytic converter, it could be a lean air fuel mixture, or retarded ignition timing all of the above should cause a loss of power or fuel economy.

    Flag This

  • Reply

    Visitor, May 09, 2011, 18:46

    Patrick, thanks for the response. We removed the exhaust to see if it made a change, no still the same. We did a smoke test for vacuum leaks, none found. The engine has good power at all ranges and no dead spots when given gas. at idle it seems to be ok. But if you increase the engine rpms to 1500 or above the exhaust manifolds get over 1000 degrees, the block is still cool enough that the thermostat hasn't opened around 136 degrees. as it reaches temp to open it does and cooling fans come on when called for by the ect. This one has me a little loopy not sure what I,m over looking?????

    Reply
    Flag This

  • Answer #2

    macdad November 02, 2011, 07:37
    Profile_thumbnail
     Enthusiast

    The only reason the exhaust manifolds can be turning red - when everything else is working properly - is that they are made of thinner metal and not the solid cast iron used in older manifolds. Thinner metal cannot conduct heat fast enough. Make sure nothing that can melt is near and definitely not touching the manifolds.

    Reply
    Flag This
Answer Ranks

This week's top 10

1 globalhelper 6 carpetvan2
2 milesauto 7 obdcar
3 csubak30 8 2004toycam
4 jose8889 9 Transmission-Tech
5 Merrimack Auto 10 Camster