Overheating, there is excessive pressure building up into cooling system

DENVBRONCOS

MEMBER
1990 VOLVO 740
2.3L
4 CYL
2WD
AUTOMATIC
357,000 MILES

Enough to blow off smaller heater return hose. Removed all spark plugs and and inserted one at a time. And turned over car to see if pressure pushed water out of full overflow tank. Is this a good test to determine if head gasket is blown?

Sunday, June 9th, 2019 AT 6:00 PM

7 Replies

KASEKENNY

MECHANIC
18,907 POSTS

Hi Denvbroncos,

Unfortunately, this is not definitive. However, you have a very good sign of a head gasket issue with excess pressure in the cooling system.

Here is a guide that will take you through the best ways to determine a head gasket issue:

https://www.2carpros.com/articles/head-gasket-blown-test

https://www.2carpros.com/articles/how-to-test-engine-compression

If you don't have some of these tools, you can rent them from the parts stores but I would start with a compression test. This will be the most definitive. You can then perform a cylinder leakage test but if you have low compression then you pretty much know that it is leaking into the coolant passages. A cylinder leakage test will tell you where you are losing your compression.

Let me know what you find and I will be happy to assist further if needed. Thanks

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Sunday, June 9th, 2019 AT 6:44 PM

DENVBRONCOS

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20 POSTS

I think it's the gasket looked into number two cylinder after cranking it over and there was a few droplets of water in combustion chamber. Car runs fine. A little hard to start. No water in the oil and all cylinders are firing. What do you think?

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Sunday, June 9th, 2019 AT 7:53 PM

DENVBRONCOS

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I will do tests but don't have the tools right now. Head gasket was changed. Head was resurfaced but a few water jackets had a little corrosion that made them larger than they should be. Head wasn't pressure tested. I think maybe a good idea to take head back off and get pressure tested. Or possible try something Blue Devil since the leak isn't really bad yet?

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Sunday, June 9th, 2019 AT 7:57 PM

KASEKENNY

MECHANIC
18,907 POSTS

Okay. Just make sure if you are going to use an additive like this, that you do it sooner than later because they do not fix leaks like they lead you to believe (or out right state) they just delay them. If it is small enough it may plug it but when they are this small to be plugged the engine usually doesn't exhibit an issue so why would you use it if you don't see an issue yet? By the time you see the symptoms it is usually too late for this to fix the problem, but you can slow it down or delay the inevitable.

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Monday, June 10th, 2019 AT 2:55 PM

JIS001