As I was driving, I heard this snap from the engine compartment that was accompanied by my rpm racing to 2000. I pulled over with the car in neutral and opened the hood while the engine was still racing. I checked the throttle wire and it was in the idle position! After checking for a possible cause, I noticed the the cap and insert for a component on the hose leading from the intake manifold to the brake booster was missing. I stuffed the component cavity with paper which allowed the rpm to drop to normal? To date, I have not been able to identify the component in a manual or Volvo vender parts list to order a replacement. I have surveyed other 1800 engine compartment photos and not all of them have this. Questions: 1. What is this component? 2. What is its purpose? Where can I get a replacement?
Thanks,

Two things that you can try tu use a valve with smaller barbs -

1, put a small section of the correct hose on first, then attach the larger hose. Find a hose the proper thickness. I always keep any hoses that I come across and some hoses from appliances are quite thin.

2. Wrap the barbs with electrical tape to get the proper diameter than attach the hose. Clamp the hose tight and check it once and a while - vacuum is a small but irrestable force and may cause the tape to slowly move.

I was able to purchase a proper size replacement from Planetman. Thanks anyway for the tip. Also, I was wrong about a screw on cap. It is a snap in cap.

Grepory;

I agree with C1800...I believe some Check Valves on the vacuum line to Brake Booster are plastic, but that is the first time I've heard of one exploding with a snap, then disappearing...! Some vintages of Brake Booster have them at Vacuum fitting, and not separately in-line.

You should give year when asking questions, but "throttle wire" suggests Fuel Injected...

Cheers

My car is a fuel injected 1970 1800E. I have concluded that the snap I heard was the screw-on cap that came off and hit a fan blade. I'll order a replacement that Eric might have in store.

Screw on cap? Be sure what you are ordering. I don't connect screw on cap with a servo non return valve.

Likely the check valve leading to the brake booster. How were your brakes after the incident? Check valve available from the usual classic Volvo suppliers.

I agree and it sounds like the inline vacuum check valve for the brake booster came apart which is a not too uncommon occurrence especially if the it's the original check valve.

AFAIK, no one sells the exact correct inline check valve and that is Volvo's fault.

Volvo updated the brake booster check valve, but to a vacuum check valve used on 240/260. And although functionally the same, the problem is that hose barbs on the updated check valve are smaller than the original.

You can use that valve, but it requires that you over-tighten the hose clamps on brake booster and that will shorten the life of the hose.

When I discovered this problem 30 years ago, I found another check valve made by the same manufacturer that has the correct sized hose barbs.


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Eric
Hi Performance Automotive Service (formerly OVO or Old Volvos Only)
Torrance, CA 90502
hiperformanceautoservice.com or oldvolvosonly.com

Eric,
What is the make & part number for the brake check valve hat fits these injected 1800e's ? ATE?
Thanks, Duck

The original Volvo part number for the check valve with the correct sized hose barbs was 680467, but Volvo updated it to a 1228272 and then updated it to 9485451.

As I said, you can use the check valve with the smaller hose barbs by tightening the hose clamps, but that can damage the hose.

FYI, we sell the check valves that are made by ATE with the correct sized hose barbs for $15.00 while Volvo sells the incorrect sized check valves for $31.00.



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Eric
Hi Performance Automotive Service (formerly OVO or Old Volvos Only)
Torrance, CA 90502
hiperformanceautoservice.com or oldvolvosonly.com

Eric, I would like to purchase the check valve you described as fitting on the original hose size. Let me know the purchase arrangement and I will submit payment. MBambo@comcast.net