Coolant expansion


cskins

New member
I have a 1985 1.9 litre Westfalia. I have been having problems with the cooling system. While driving, the coolant expands and overflows to the point where the van begins to overheat. I just performed a leakdown test and only #3 came out in the low end of low high end of moderate around 35 percent. When I run the engine with the main coolant bottle open I can see gas and foam as I rev the engine. I think I may have a leaky head gasket but How do I find out which side or do a definitive test.
 

scotsborn

New member
OK. Let's take a step back and review what we know.

1. You have 35 percent leak down on cylinder #3
2. You have coolant overflowing when you run the engine and the engine overheats when driving

Although you have two issues they may not be related. It would be my opinion to treat them as seperate issues until you find definitive proof that they have one and the same root cause. Since you probably discovered issue number 1 while looking for the cause of number 2 I would suggest we start at number 2 and find the root cause of that first.

Now, coolant under pressure has a higher boiling point so we have to make sure your pressure cap is working properly and you don't have a leak elsewhere. Get your cap checked out or failing all else replace it with another as it is possibly 26 years old at this point. Once you have checked that out then we can move onto the 'bubbles' as you rev the engine. Since you have a leakdown tester you can pressurize each cylinder individually. So, get the engine hot. put your leakdown tester on a cylinder, pressurize it and then wait while observing the cooling system. If you spot bubbles right away then you've identified where the issue is but be aware that the issue may only appear at a given temperature so be prepared to let the engine cool down a little with the pressure still applied to see if the bubbles increase /decrease while the temperature changes. If you find the cylinder that is introducing pressure into the cooling system right away then you have the source of your coolant loss / overheating issue. Repeat for all cylinders.

Your leakdown test has proven that one cylinder us at 35% but how does that compare to the others? If the others are at 25% then the difference is only 10%. If the engine has 250k on it then that might be expected. Your leakdown test is determining the ability of your combustion chamber to hold pressure. Where that leakage is going is the important issue. You should be listening to the intake, exhaust and crankcase to determine where the 'noise' is loudest as that will be the indicator of root cause. For example, if the intake is loud then the valves would be suspect with the same results on the exhaust. If the crankcase is loudest then the rings/pistons/cylinder bores would be the likely cause.

If your leakdown test provides bubbles in the coolant then you can also say that your head gasket interface is an issue. This would cause you to pull the head and inspect for cracks, head gasket failure etc. Once you have determined the likely area of concern then you have to decide what is the best course of action. Is it to rebuild the heads? The whole motor? Put in a used one? Lets see where your diagnosis goes first.

Use the leakdown test wisely and check for leaks before tearing the motor apart. It would be a bummer to pull the head due to the coolant issue only to have a valve issue when it is reassembled. Do all of your diagnosis and note the readings carefully. This will be very helpful when trying to determine the best course of action when the root cause is discovered.

Keep us posted on your progress.
 

cskins

New member
Been a little slow on the reply but the news is good. Coolant recovery tank cap fixed the problem. The leakdown test showed loss due to ring wear. So all is well until the next issue.
 

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