my 68 ninety-eight has a problem . restored 3 years ago , ran great all summer ,but this past month i took out of storage and started it it overheated boiled over while i was not looking guess the thermoostat stuck now it runs bad and no vacum at brakes . 1 . could it have a blown head gasket , or intake manifold gasket . how would I check this . i put new plugs in and dont change , the old ones seemed alright tips light brown

rocwal
Dan B

 

There are sniffers which will detect combustion gas in the coolant ...
remove the thermostat and you can see exhaust gas as bubbles...

 

How cold was it when it was in storage? How much anti-freeze was in it?
What temp was the anti-freeze set at?

Sounds like the intake gasket is bad. Also the head gasket may have blown. Does it over heat now while it is running bad?

Gene

 

One of the first things you should do is a compression test. If two cylinders side by side have low compresssion then you know the head gasket is blown there.

 

Hey;Did you check the vacuum line(booster) to see if it was damaged ? Would cause a big vacuum leak > engine runs bad.

 

Thanks . the antifreeze was at 25- and weather was in the 30's . How would a intake gasket blow it metal ? have not done a compress test yet . or checked the vacum pressuer . so damm upset I think my Ex or her friend s did some thing to it . seems everytime i start it , it runs worse than before . think i will drain the gas tank first or use a can to try next time in case something was put in gas .

rocwal
Dan B

 

What was the initial indication of overheating? Temp light on?
Prolonged overheating ~could have~ but hopefully not warped the heads, simulating a blown head gasket...

Do check all hoses for damage. Where was it stored? Rodents, just like exes (and in same catagory) can do lots of damage to rubber parts.

Sounds like you need a guard dog to keep the exes away.

PS - enjoy some good fresh Maine lobster for me, will ya...

 

Well i took the thermostat out that i installed last spring and it just barely opened in boiling water so problem of overheating partly solved . disconnected gas lines at fuel pump and run lines to gas can , runs much better so i dropped tank cleaned it and found a lot of little black flecks of something , changed the filter on carb it also has same stuff on it , dont know if someone put anything in tank to sabatoge car ?? tomorrow i will check vacum from intake manifold ,and compression test on cylinders ,then put the SUN machine on it for other tests , I hope i dont find any blown gaskets. Any one know about the thermostat that is supposed to stay open if it goes bad instead of staying closed and making engine overheat , also how much vacum should i get from test ,also compression on cylinders ??

rocwal
Dan B

 

I would think on a fairly stock 455 you should get at least 18" of vacuum at idle. Also pull the line to the brake booster and cover it with your thumb and see if the idle smooths out at all.
My booster went out last year and the car ran like utter CRAP. It sounded like a hoover under the hood coming out the scoops. I couldn't swap out the booster fast enough.

 

OK . I checked the vacum and very little about 5-7 inchs . checked the compression got 210 -212 on all but #2 and #4 none . IS it blown head gasket or valves ?

rocwal Dan B